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Chemistry

Kenneth W. Whitten, Raymond E. Davis, Larry Peck

Chapter 15

Chemical Thermodynamics - all with Video Answers

Educators

Chapter Questions

01:10

Problem 1

State precisely the meaning of each of the following terms. You may need to review Chapter 1 to refresh your memory concerning terms introduced there. (a) energy; (b) kinetic energy; (c) potential energy; (d) joule.

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:31

Problem 2

State precisely the meaning of each of the following terms. You may need to review Chapter 1 to refresh your memory about terms introduced there. (a) heat; (b) temperature;
(c) system; (d) surroundings; (e) thermodynamic state of system; (f) work.

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:09

Problem 3

(a) Give an example of the conversion of heat into work.
(b) Give an example of the conversion of work into heat.

Shubham Kanungo
Shubham Kanungo
Numerade Educator
00:50

Problem 4

(a) Give an example of heat being given off by the system.
(b) Give an example of work being done on the system.

Shubham Kanungo
Shubham Kanungo
Numerade Educator
00:47

Problem 5

(a) Give an example of heat being added to the system.
(b) Give an example of work being done by the system.

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:35

Problem 6

Distinguish between endothermic and exothermic processes. If we know that a reaction is endothermic in one direction, what can be said about the reaction in the reverse direction?

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:29

Problem 7

According to the First Law of Thermodynamics, the total amount of energy in the universe is constant. Why, then, do we say that we are experiencing a declining supply of energy?

Shubham Kanungo
Shubham Kanungo
Numerade Educator
00:47

Problem 8

Use the First Law of Thermodynamics to describe what occurs when an incandescent light is turned on.

Shubham Kanungo
Shubham Kanungo
Numerade Educator
00:53

Problem 9

Define enthalpy and give an example of a reaction that has a negative enthalpy change.

Shubham Kanungo
Shubham Kanungo
Numerade Educator
02:55

Problem 10

Which of the following are examples of state functions? (a) your bank balance; (b) the mass of a candy bar; (c) your weight; (d) the heat lost by perspiration during a climb up a mountain along a fixed path.

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:53

Problem 11

What is a state function? Would Hess's Law be a law if enthalpy were not a state function?

Shubham Kanungo
Shubham Kanungo
Numerade Educator
06:48

Problem 12

(a) Distinguisl? between $\Delta H$ and $\Delta H^{0}$ for a reaction.
(b) Distinguish between $\Delta H_{\mathrm{rm}}^{0}$ and $\Delta H_{\mathrm{f}}^{0}$

Sandra Lundell
Sandra Lundell
Numerade Educator
01:10

Problem 13

A reaction is characterized by $\Delta H_{\mathrm{rm}}=+450 \mathrm{~kJ} /$ mol. Does the reaction mixture absorb heat from the surroundings or release heat to them?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:57

Problem 14

For each of the following reactions, (a) does the enthalpy increase or decrease; (b) is $H_{\text {reactants }}>H_{\text {products }}$ or is $H_{\text {products }}>H_{\text {reactants }} ;$ (c) is $\Delta H$ positive or negative?
(i) $\mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{~s}) \longrightarrow 2 \mathrm{Al}(\mathrm{s})+\frac{3}{2} \mathrm{O}_{2}(\mathrm{~g})$
(endothermic) (ii) $\mathrm{Sn}(\mathrm{s})+\mathrm{Cl}_{2}(\mathrm{~g}) \longrightarrow \mathrm{SnCl}_{2}(\mathrm{~s}) \quad$ (exothermic)

Shubham Kanungo
Shubham Kanungo
Numerade Educator
03:21

Problem 15

(a) The combustion of $0.0222 \mathrm{~g}$ of isooctane vapor, $\mathrm{C}_{8} \mathrm{H}_{18}(\mathrm{~g})$, at constant pressure raises the temperature of a calorimeter $0.400^{\circ} \mathrm{C}$. The heat capacity of the calorimeter and water combined is $2.48 \mathrm{~kJ} /{ }^{\circ} \mathrm{C}$. Find the molar heat of combustion of gaseous isooctane.
$$\mathrm{C}_{8} \mathrm{H}_{18}(\mathrm{~g})+12 \frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 8 \mathrm{CO}_{2}(\mathrm{~g})+9 \mathrm{H}_{2} \mathrm{O}(\ell)$$
(b) How many grams of $\mathrm{C}_{8} \mathrm{H}_{18}(\mathrm{~g})$ must be burned to obtain $495 \mathrm{~kJ}$ of heat energy?

Shubham Kanungo
Shubham Kanungo
Numerade Educator
02:45

Problem 16

Methanol, $\mathrm{CH}_{3} \mathrm{OH}$, is an efficient fuel with a high octane rating.
$\mathrm{CH}_{3} \mathrm{OH}(\mathrm{g})+\frac{3}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\ell)$
$\Delta H=-764 \mathrm{~kJ} / \mathrm{mol} \mathrm{rxn}$ (a) Find the heat evolved when $115.0 \mathrm{~g} \mathrm{CH}_{3} \mathrm{OH}(\mathrm{g})$ burns in excess oxygen. (b) What mass of $\mathrm{O}_{2}$ is consumed when $925 \mathrm{~kJ}$ of heat is given off?

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:20

Problem 17

How much heat is liberated when $0.113$ mole of sodium reacts with excess water according to the following equation?
$2 \mathrm{Na}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow \mathrm{H}_{2}(\mathrm{~g})+2 \mathrm{NaOH}(\mathrm{aq})$
$\Delta H=-368 \mathrm{~kJ} / \mathrm{mol} \mathrm{rxn}$

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:19

Problem 18

What is $\Delta H$ for the reaction
$$\mathrm{PbO}(\mathrm{s})+\mathrm{C}(\mathrm{s}) \longrightarrow \mathrm{Pb}(\mathrm{s})+\mathrm{CO}(\mathrm{g})$$
if $5.95 \mathrm{~kJ}$ must be supplied to convert $13.43 \mathrm{~g}$ lead(II) oxide to lead?

Shubham Kanungo
Shubham Kanungo
Numerade Educator
00:46

Problem 19

From the data in Appendix $\mathrm{K}$, determine the form that represents the standard state for each of the following elements: iodine, oxvgen, sulfur.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:28

Problem 20

Why is the standard molar enthalpy of formation, $\Delta H_{\mathrm{f}}^{0}$ for liquid water different than $\Delta H_{\mathrm{f}}^{0}$ for water vapor, both at $25^{\circ} \mathrm{C} ?$ Which formation reaction is more exothermic? Does your answer indicate that $\mathrm{H}_{2} \mathrm{O}(\ell)$ is at a higher or lower enthalpy than $\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) ?$

David Collins
David Collins
Numerade Educator
03:04

Problem 21

Methylhydrazine is burned with dinitrogen tetroxide in the attitude-control engines of the space shuttles.
$\mathrm{CH}_{6} \mathrm{~N}_{2}(\ell)+\frac{5}{4} \mathrm{~N}_{2} \mathrm{O}_{4}(\ell) \longrightarrow$
$$\mathrm{CO}_{2}(\mathrm{~g})+3 \mathrm{H}_{2} \mathrm{O}(\ell)+\frac{9}{4} \mathrm{~N}_{2}(\mathrm{~g})$$
The two substances ignite instantly on contact, producing a flame temperature of $3000 . \mathrm{K}$. The energy liberated per $0.100 \mathrm{~g}$ of $\mathrm{CH}_{6} \mathrm{~N}_{2}$ at constant atmospheric pressure after the products are cooled back to $25^{\circ} \mathrm{C}$ is $750 . \mathrm{J} .$ (a) Find $\Delta H$ for the reaction as written. (b) How many kilojoules are liberated when $87.5 \mathrm{~g}$ of $\mathrm{N}_{2}$ is produced?

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:20

Problem 22

Which is more exothermic, the combustion of one mole of methane to form $\mathrm{CO}_{2}(\mathrm{~g})$ and liquid water or the combustion of one mole of methane to form $\mathrm{CO}_{2}(\mathrm{~g})$ and steam? Why? (No calculations are necessary.)

David Collins
David Collins
Numerade Educator
01:25

Problem 23

Which is more exothermic, the combustion of one mole of gaseous benzene, $\mathrm{C}_{6} \mathrm{H}_{6}$, or the combustion of one mole of liquid benzene? Why? (No calculations are necessary.)

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:07

Problem 24

Explain the meaning of the phrase "thermodynamic standard state of a substance."

David Collins
David Collins
Numerade Educator
01:11

Problem 25

Explain the meaning of the phrase "standard molar enthalpy of formation." Give an example.

David Collins
David Collins
Numerade Educator
01:03

Problem 26

From the data in Appendix $\mathrm{K}$, determine the form that represents the standard state for each of the following elements: (a) chlorine, (b) chromium, (c) bromine,
(d) iodine, (e) sulfur, (f) nitrogen.

David Collins
David Collins
Numerade Educator
00:39

Problem 27

From the data in Appendix $\mathrm{K}$, determine the form that represents the standard state for each of the following elements: (a) oxygen, (b) carbon, (c) phosphorus,
(d) rubidium, (e) mercury, (f) tin.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:44

Problem 28

Write the balanced chemical equation whose $\Delta H_{\text {ren }}^{0}$ value is equal to $\Delta H_{\mathrm{f}}^{0}$ for each of the following substances:
(a) calcium hydroxide, $\mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{~s}) ;$ (b) benzene, $\mathrm{C}_{6} \mathrm{H}_{6}(\ell)$;
(c) sodium bicarbonate, $\mathrm{NaHCO}_{3}(\mathrm{~s}) ;$ (d) calcium fluoride, $\mathrm{CaF}_{2}(\mathrm{~s}) ;(\mathrm{e})$ phosphine, $\mathrm{PH}_{3}(\mathrm{~g}) ;$ (f) propane, $\mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g}) ;$
(g) atomic sulfur, $\mathrm{S}(\mathrm{g}) ;$ (h) water, $\mathrm{H}_{2} \mathrm{O}(\ell)$.

Aadit Sharma
Aadit Sharma
Numerade Educator
02:15

Problem 29

Write the balanced chemical equation for the formation of one mole of each of the following substances from its elements in the standard state (the equation whose $\Delta H_{\mathrm{rxn}}^{0}$ value is equal to $\Delta H_{\mathrm{f}}^{0}$ for the substance):
hydrogen peroxide $\left[\mathrm{H}_{2} \mathrm{O}_{2}(\ell)\right]$, calcium fluoride $\left[\mathrm{CaF}_{2}(\mathrm{~s})\right]$, ruthenium(III) hydroxide $\left[\mathrm{Ru}(\mathrm{OH})_{3}(\mathrm{~s})\right]$.

Anthony Han
Anthony Han
Numerade Educator
01:28

Problem 30

We burn $3.47 \mathrm{~g}$ of lithium in excess oxygen at constant atmospheric pressure to form $\mathrm{Li}_{2} \mathrm{O} .$ Then we bring the reaction mixture back to $25^{\circ} \mathrm{C}$. In this process $146 \mathrm{~kJ}$ of heat is given off. What is the standard molar enthalpy of formation of $\mathrm{Li}_{2} \mathrm{O}$ ?

Lottie Adams
Lottie Adams
Numerade Educator
02:32

Problem 31

We burn $8.10 \mathrm{~g}$ of magnesium in excess nitrogen at constant atmospheric pressure to form $\mathrm{Mg}_{3} \mathrm{~N}_{2} .$ Then we bring the reaction mixture back to $25^{\circ} \mathrm{C}$. In this process $76.83 \mathrm{~kJ}$ of heat is given off. What is the standard molar enthalpv of formation of $\mathrm{Mg}_{2} \mathrm{~N}_{2}$ ?

Aadit Sharma
Aadit Sharma
Numerade Educator
02:21

Problem 32

From the following enthalpies of reaction,
$4 \mathrm{HCl}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(\ell)+2 \mathrm{Cl}_{2}(\mathrm{~g})$
$\Delta H=-202.4 \mathrm{~kJ} / \mathrm{mol} \mathrm{rxn}$
$\frac{1}{2} \mathrm{H}_{2}(\mathrm{~g})+\frac{1}{2} \mathrm{~F}_{2}(\mathrm{~g}) \longrightarrow \mathrm{HF}(\ell)$
$\Delta H=-600.0 \mathrm{~kJ} / \mathrm{mol} \mathrm{rxn}$
$\mathrm{H}_{2}(\mathrm{~g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{H}_{2} \mathrm{O}(\ell)$
$\Delta H=-285.8 \mathrm{~kJ} / \mathrm{mol} \mathrm{rxn}$
find $\Delta H_{\mathrm{ran}}$ for $2 \mathrm{HCl}(\mathrm{g})+\mathrm{F}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{HF}(\ell)+\mathrm{Cl}_{2}(\mathrm{~g})$.

Aadit Sharma
Aadit Sharma
Numerade Educator
02:51

Problem 33

From the following enthalpies of reaction,
$$\begin{aligned}\mathrm{CaCO}_{3}(\mathrm{~s}) \longrightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g}) \\
\Delta H=-178.1 \mathrm{~kJ} / \mathrm{mol} \mathrm{rxn} \\
\mathrm{CaO}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow \mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{~s}) \\
\Delta H=-65.3 \mathrm{~kJ} / \mathrm{mol} \mathrm{rxn} \\
\mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{~s}) \longrightarrow \mathrm{Ca}^{2+}(\mathrm{aq})+2 \mathrm{OH}^{-}(\mathrm{aq}) \\
\Delta H=-16.2 \mathrm{~kJ} / \mathrm{mol} \mathrm{rxn}
\end{aligned}$$
calculate $\Delta H_{\mathrm{rxn}}$ for
$$\mathrm{Ca}^{2+}(\mathrm{aq})+2 \mathrm{OH}^{-}(\mathrm{aq})+\mathrm{CO}_{2}(\mathrm{~g}) \longrightarrow$$

Shubham Kanungo
Shubham Kanungo
Numerade Educator
02:09

Problem 34

Given that
$$\begin{aligned}\mathrm{S}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{SO}_{2}(\mathrm{~g}) & \Delta H &=-296.8 \mathrm{~kJ} / \mathrm{mol} \\\mathrm{S}(\mathrm{s})+\frac{3}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{SO}_{3}(\mathrm{~g}) & \Delta H &=-395.6 \mathrm{~kJ} / \mathrm{mol}\end{aligned}$$
determine the enthalpy change for the decomposition reaction
$$2 \mathrm{SO}_{3}(\mathrm{~g}) \longrightarrow 2 \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g})$$

Anthony Han
Anthony Han
Numerade Educator
01:46

Problem 35

Evaluate $\Delta H_{\mathrm{rxn}}^{0}$ for the reaction below at $25^{\circ} \mathrm{C}$, using the heats of formation.
$$\begin{array}{rrrr} & \mathrm{Fe}_{3} \mathrm{O}_{4}(\mathrm{~s})+\mathrm{CO}(\mathrm{g}) \longrightarrow & 3 \mathrm{FeO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g}) \\
\Delta H_{\mathrm{f}}^{0}, \mathrm{~kJ} / \mathrm{mol}: & -1118 & -110.5 & -272 & -393.5\end{array}$$

Anthony Han
Anthony Han
Numerade Educator
02:31

Problem 36

Given that
$$\begin{array}{r}2 \mathrm{H}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(\ell) \\
\Delta H=-571.6 \mathrm{~kJ} / \mathrm{mol} \\
\mathrm{C}_{3} \mathrm{H}_{4}(\mathrm{~g})+4 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 3 \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \\
\Delta H=-1937 \mathrm{~kJ} / \mathrm{mol} \\
\mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 3 \mathrm{CO}_{2}(\mathrm{~g})+4 \mathrm{H}_{2} \mathrm{O}(\ell) \\\Delta H=-2220 . \mathrm{kJ} / \mathrm{mol}\end{array}$$
determine the heat of the hydrogenation reaction
$$\mathrm{C}_{3} \mathrm{H}_{4}(\mathrm{~g})+2 \mathrm{H}_{2}(\mathrm{~g}) \longrightarrow \mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g})$$

Anthony Han
Anthony Han
Numerade Educator
01:57

Problem 37

Determine the heat of formation of liquid hydrogen peroxide at $25^{\circ} \mathrm{C}$ from the following thermochemical equations.
$\mathrm{H}_{2}(\mathrm{~g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$
$\Delta H^{0}=-241.82 \mathrm{~kJ} / \mathrm{mol}$
$2 \mathrm{H}(\mathrm{g})+\mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$
$\Delta H^{0}=-926.92 \mathrm{~kJ} / \mathrm{mol}$
$2 \mathrm{H}(\mathrm{g})+2 \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{~g})$
$\begin{aligned} \Delta H^{0} &=-1070.60 \mathrm{~kJ} / \mathrm{mol} \\ 2 \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{O}_{2}(\mathrm{~g}) & \Delta H^{0}=-498.34 \mathrm{~kJ} / \mathrm{mol} \\ \mathrm{H}_{2} \mathrm{O}_{2}(\ell) \longrightarrow \mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{~g}) & \Delta H^{0}=51.46 \mathrm{~kJ} / \mathrm{mol} \end{aligned}$

Aadit Sharma
Aadit Sharma
Numerade Educator
04:12

Problem 38

Use data in Appendix $\mathrm{K}$ to find the enthalpy of reaction for
(a) $\mathrm{NH}_{4} \mathrm{NO}_{3}(\mathrm{~s}) \longrightarrow \mathrm{N}_{2} \mathrm{O}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(\ell)$
(b) $2 \mathrm{FeS}_{2}(\mathrm{~s})+\frac{11}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{~s})+4 \mathrm{SO}_{2}(\mathrm{~g})$
(c) $\mathrm{SiO}_{2}(\mathrm{~s})+3 \mathrm{C}$ (graphite) $\longrightarrow \mathrm{SiC}(\mathrm{s})+2 \mathrm{CO}(\mathrm{g})$

Sandra Lundell
Sandra Lundell
Numerade Educator
04:22

Problem 39

Repeat Exercise 38 for
(a) $\mathrm{CaCO}_{3}(\mathrm{~s}) \longrightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g})$
(b) $2 \mathrm{HI}(\mathrm{g})+\mathrm{F}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{HF}(\mathrm{g})+\mathrm{I}_{2}(\mathrm{~s})$
(c) $\mathrm{SF}_{6}(\mathrm{~g})+3 \mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow 6 \mathrm{HF}(\mathrm{g})+\mathrm{SO}_{3}(\mathrm{~g})$

Sandra Lundell
Sandra Lundell
Numerade Educator
02:26

Problem 40

The internal combustion engine uses heat produced during the burning of a fuel. Propane, $\mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g})$, is sometimes used as the fuel. Gasoline is the most commonly used fuel. Assume that the gasoline is pure octane, $\mathrm{C}_{8} \mathrm{H}_{18}(\ell)$, and the fuel and oxygen are completely converted into $\mathrm{CO}_{2}(\mathrm{~g})$ and $\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) .$ For each of these fuels, determine the heat released per gram of fuel burned.

David Collins
David Collins
Numerade Educator
02:17

Problem 41

Write the balanced equation for the complete combustion (in excess $\mathrm{O}_{2}$ ) of kerosene. Assume that kerosene is $\mathrm{C}_{10} \mathrm{H}_{22}(\ell)$ and that the products are $\mathrm{CO}_{2}(\mathrm{~g})$ and $\mathrm{H}_{2} \mathrm{O}(\ell) .$
Calculate $\Delta H_{\mathrm{rxn}}^{0}$ at $25^{\circ} \mathrm{C}$ for this reaction. $\Delta H_{\mathrm{f}}^{0} \mathrm{C}_{10} \mathrm{H}_{22}(\ell)=-249.6 \mathrm{~kJ} / \mathrm{mol}$
$\Delta H_{\mathrm{f}}^{0} \mathrm{CO}_{2}(\mathrm{~g})=-393.5 \mathrm{~kJ} / \mathrm{mol}$
$\Delta H_{\mathrm{f}}^{0} \mathrm{H}_{2} \mathrm{O}(\ell)=-285.8 \mathrm{~kJ} / \mathrm{mol}$

Aadit Sharma
Aadit Sharma
Numerade Educator
03:02

Problem 42

The thermite reaction, used for welding iron, is the reaction of $\mathrm{Fe}_{3} \mathrm{O}_{4}$ with $\mathrm{Al}$.
$8 \mathrm{Al}(\mathrm{s})+3 \mathrm{Fe}_{3} \mathrm{O}_{4}(\mathrm{~s}) \longrightarrow 4 \mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{~s})+9 \mathrm{Fe}(\mathrm{s})$
$\Delta H^{0}=-3350 . \mathrm{kJ} / \mathrm{mol} \mathrm{rxn}$
Because this large amount of heat cannot be rapidly dissipated to the surroundings, the reacting mass may reach temperatures near $3000 .^{\circ} \mathrm{C}$. How much heat is released by the reaction of $27.6 \mathrm{~g}$ of $\mathrm{Al}$ with $69.12 \mathrm{~g}$ of $\mathrm{Fe}_{3} \mathrm{O}_{4} ?$

Anthony Han
Anthony Han
Numerade Educator
02:04

Problem 43

When a welder uses an acetylene torch, the combustion of acetylene liberates the intense heat needed for welding metals together. The equation for this combustion reaction is
$$2 \mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 4 \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$$
The heat of combustion of acetylene is $-1255.5 \mathrm{~kJ} / \mathrm{mol}$ of $\mathrm{C}_{2} \mathrm{H}_{2}$. How much heat is liberated when $1.731 \mathrm{~kg}$ of $\mathrm{C}_{2} \mathrm{H}_{2}$
is burned?

Anthony Han
Anthony Han
Numerade Educator
02:38

Problem 44

Write balanced equations for the oxidation of sucrose (a carbohydrate) and tristearin (a fat). Assume that each reacts with $\mathrm{O}_{2}(\mathrm{~g})$, producing $\mathrm{CO}_{2}(\mathrm{~g})$ and $\mathrm{H}_{2} \mathrm{O}(\mathrm{g})$. Use tabulated bond energies to estimate $\Delta H_{\mathrm{ran}}^{0}$ for each reaction in $\mathrm{kJ} / \mathrm{mol}$ (ignoring phase changes). Convert to $\mathrm{kJ} / \mathrm{g}$ and $\mathrm{kcal} / \mathrm{g}$. Which has the greater energy density?

Nicole Smina
Nicole Smina
Numerade Educator
04:13

Problem 45

Natural gas is mainly methane, $\mathrm{CH}_{4}(\mathrm{~g})$. Assume that gasoline is octane, $\mathrm{C}_{8} \mathrm{H}_{18}(\ell)$, and that kerosene $\mathrm{is}$ $\mathrm{C}_{10} \mathrm{H}_{22}(\ell) .(\mathrm{a})$ Write the balanced equations for the combustion of each of these three hydrocarbons in excess $\mathrm{O}_{2} .$ The products are $\mathrm{CO}_{2}(\mathrm{~g})$ and $\mathrm{H}_{2} \mathrm{O}(\ell) .(\mathrm{b})$
Calculate at $25^{\circ} \mathrm{C}$ for each combustion reaction. $\Delta H_{\mathrm{f}}^{0}$ for $\mathrm{C}_{10} \mathrm{H}_{22}$ is $-300.9 \mathrm{~kJ} / \mathrm{mol} .$ (c) When burned at standard conditions, which of these three fuels would produce the most heat per mole? (d) When burned at standard conditions, which of the three would produce the most heat per gram?

David Collins
David Collins
Numerade Educator
01:25

Problem 46

(a) How is the heat released or absorbed in a gas phase reaction related to bond energies of products and reactants?
(b) Hess's Law states that
$$\Delta H_{\mathrm{rxn}}^{0}=\Sigma n \Delta H_{\mathrm{f} \text { products }}^{0}-\Sigma n \Delta H_{\text {freactants }}^{0}$$
The relationship between $\Delta H_{\text {ran }}^{0}$ and bond energies for a gas pbase reaction is
$\Delta H_{\mathrm{ran}}^{0}=\Sigma$ bond energies_{reactants } $-\Sigma$ bond energies $_{\text {produets }}$
It is not true, in general, that $\Delta H_{\mathrm{f}}^{0}$ for a substance is equal to the negative of the sum of the bond energies of the substance. Why?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:53

Problem 47

(a) Suggest a reason for the fact that different amounts of energy are required for the successive removal of the three hydrogen atoms of an ammonia molecule, even though all $\mathrm{N}-\mathrm{H}$ bonds in ammonia are equivalent. (b) Suggest why the $\mathrm{N}-\mathrm{H}$ bonds in different compounds such as ammonia, $\mathrm{NH}_{3} ;$ methylamine, $\mathrm{CH}_{3} \mathrm{NH}_{2}$; and ethylamine, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NH}_{2}$, have slightly different bond energies.

Anthony Han
Anthony Han
Numerade Educator
03:53

Problem 48

Use tabulated bond energies to estimate the enthalpy of reaction for each of the following gas phase reactions.
(a) $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}+\mathrm{Br}_{2} \longrightarrow \mathrm{BrH}_{2} \mathrm{C}-\mathrm{CH}_{2} \mathrm{Br}$
(b) $\mathrm{H}_{2} \mathrm{O}_{2} \longrightarrow \mathrm{H}_{2} \mathrm{O}+\frac{1}{2} \mathrm{O}_{2}$

Aadit Sharma
Aadit Sharma
Numerade Educator
08:55

Problem 49

Use tabulated bond energies to estimate the enthalpy of reaction for each of the following gas phase reactions.
(a) $\mathrm{N}_{2}+3 \mathrm{H}_{2} \longrightarrow 2 \mathrm{NH}_{3}$
(b) $\mathrm{CH}_{4}+\mathrm{Cl}_{2} \longrightarrow \mathrm{CH}_{3} \mathrm{Cl}+\mathrm{HCl}$
(c) $\mathrm{CO}+\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{CO}_{2}+\mathrm{H}_{2}$

Sandra Lundell
Sandra Lundell
Numerade Educator
01:36

Problem 50

Use the bond energies listed in Table $15-2$ to estimate the heat of reaction for

Aadit Sharma
Aadit Sharma
Numerade Educator
01:08

Problem 51

Estimate $\Delta H$ for the burning of one mole of butane, using the bond energies listed in Tables $15-2$ and $15-3$.

Aadit Sharma
Aadit Sharma
Numerade Educator
05:52

Problem 52

(a) Use the bond energies listed in Table $15-2$ to estimate the heats of formation of $\mathrm{HCl}(\mathrm{g})$ and $\mathrm{HF}(\mathrm{g}) .$ (b) Compare your answers to the standard heats of formation in Appendix $\mathrm{K}$

Sandra Lundell
Sandra Lundell
Numerade Educator
10:46

Problem 53

(a) Use the bond energies listed in Table $15-2$ to estimate the heats of formation of $\mathrm{H}_{2} \mathrm{O}(\mathrm{g})$ and $\mathrm{O}_{3}(\mathrm{~g}) .$ (b) Compare your answers to the standard heats of formation in Appendix $K$.

Sandra Lundell
Sandra Lundell
Numerade Educator
02:33

Problem 54

Using data in Appendix $\mathrm{K}$, calculate the average $\mathrm{P}-\mathrm{Cl}$ bond energy in $\mathrm{PCl}_{3}(\mathrm{~g})$.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:50

Problem 55

Using data in Appendix $\mathrm{K}$, calculate the average $\mathrm{P}-\mathrm{H}$ bond energy in $\mathrm{PH}_{3}(\mathrm{~g})$.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:38

Problem 56

Using data in Appendix $\mathrm{K}$, calculate the average $\mathrm{P}-\mathrm{Cl}$ bond energy in $\mathrm{PCl}_{5}(\mathrm{~g}) .$ Compare your answer with the value calculated in Exercise $54 .$

Aadit Sharma
Aadit Sharma
Numerade Educator
01:39

Problem 57

Methane undergoes several different exothermic reactions with gaseous chlorine. One of these forms chloroform, $\mathrm{CHCl}_{3}(\mathrm{~g})$.
Average bond energies per mole of bonds are: $\mathrm{C}-\mathrm{H}=$ $413 \mathrm{~kJ} ; \mathrm{Cl}-\mathrm{Cl}=242 \mathrm{~kJ} ; \mathrm{H}-\mathrm{Cl}=432 \mathrm{~kJ} .$ Use these to
calculate the average $\mathrm{C}-\mathrm{Cl}$ bond energy in chloroform. Compare this with the value in Table $15-2$.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:52

Problem 58

Athylamine undergoes an endothermic gas phase dissociation to produce ethylene (or ethene) and ammonia.
The following average bond energies per mole of bonds are given: $\mathrm{C}-\mathrm{H}=413 \mathrm{~kJ} ; \mathrm{C}-\mathrm{C}=346 \mathrm{~kJ} ; \mathrm{C}=\mathrm{C}=602$
$\mathrm{kJ} ; \mathrm{N}-\mathrm{H}=391 \mathrm{~kJ} .$ Calculate the $\mathrm{C}-\mathrm{N}$ bond energy in
ethylamine. Compare this with the value in Table $15-2$.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:24

Problem 59

What is a coffee-cup calorimeter? How do coffee-cup calorimeters give us useful information?

Anthony Han
Anthony Han
Numerade Educator
02:00

Problem 60

A calorimeter contained $75.0 \mathrm{~g}$ of water at $16.95^{\circ} \mathrm{C}$. A $93.3-\mathrm{g}$ sample of iron at $65.58^{\circ} \mathrm{C}$ was placed in it, giving a final temperature of $19.68^{\circ} \mathrm{C}$ for the system. Calculate the heat capacity of the calorimeter. Specific heats are $4.184 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$ for $\mathrm{H}_{2} \mathrm{O}$ and $0.444 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$ for $\mathrm{Fe}$.

David Collins
David Collins
Numerade Educator
02:27

Problem 61

A student wishes to determine the heat capacity of a coffee-cup calorimeter. After she mixes $100.0 \mathrm{~g}$ of water at $58.5^{\circ} \mathrm{C}$ with $100.0 \mathrm{~g}$ of water, already in the calorimeter, at $22.8^{\circ} \mathrm{C}$, the final temperature of the water is $39.7^{\circ} \mathrm{C}$.
(a) Calculate the heat capacity of the calorimeter in $J /{ }^{\circ} \mathrm{C}$. Use $4.184 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$ as the specific heat of water. (b) Why is it more useful to express the value in $J /{ }^{\circ} \mathrm{C}$ rather than units of $\mathrm{J} /\left(\mathrm{g}\right.$ calorimeter $\left.\cdot{ }^{\circ} \mathrm{C}\right) ?$

Aadit Sharma
Aadit Sharma
Numerade Educator
01:49

Problem 62

A coffee-cup calorimeter is used to determine the specific heat of a metallic sample. The calorimeter is filled with $50.0 \mathrm{~mL}$ of water at $25.0^{\circ} \mathrm{C}$ (density $\left.=0.997 \mathrm{~g} / \mathrm{mL}\right) . \mathrm{A}$
$36.5$ -gram sample of the metallic material is taken from water boiling at $100.0^{\circ} \mathrm{C}$ and placed in the calorimeter. The equilibrium temperature of the water and sample is $32.5^{\circ} \mathrm{C}$. The calorimeter constant is known to be $1.87 \mathrm{~J} /{ }^{\circ} \mathrm{C}$. Calculate the specific heat of the metallic material.

Aadit Sharma
Aadit Sharma
Numerade Educator
03:59

Problem 63

A $5.1$ -gram piece of gold jewelry is removed from water at $100.0^{\circ} \mathrm{C}$ and placed in a coffee-cup calorimeter containing $16.9 \mathrm{~g}$ of water at $22.5^{\circ} \mathrm{C}$. The equilibrium temperature of the water and jewelry is $23.2^{\circ} \mathrm{C}$. The calorimeter constant is known from calibration experiments to be $1.54 \mathrm{~J} /{ }^{\circ} \mathrm{C}$. What is the specific heat of this piece of jewelry? The specific heat of pure gold is $0.129 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$. Is the jewelry pure gold?

Anthony Han
Anthony Han
Numerade Educator
07:51

Problem 64

A coffee-cup calorimeter having a heat capacity of $472 \mathrm{~J} /{ }^{\circ} \mathrm{C}$ is used to measure the heat evolved when the following aqueous solutions, both initially at $22.6^{\circ} \mathrm{C}$, are mixed: $100 . \mathrm{g}$ of solution containing $6.62 \mathrm{~g}$ of lead(II) nitrate, $\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}$, and $100 . \mathrm{g}$ of solution containing $6.00 \mathrm{~g}$ of sodium iodide, NaI. The final temperature is $24.2^{\circ} \mathrm{C}$. Assume that the specific heat of the mixture is the same as that for water, $4.184 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$. The reaction is
$\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+2 \mathrm{NaI}(\mathrm{aq}) \longrightarrow \mathrm{PbI}_{2}(\mathrm{~s})+2 \mathrm{NaNO}_{3}(\mathrm{aq})$
(a) Calculate the heat evolved in the reaction.
(b) Calculate the $\Delta H$ for the reaction under the conditions of the experiment.

Anthony Han
Anthony Han
Numerade Educator
08:15

Problem 65

A coffee-cup calorimeter is used to determine the heat of reaction for the acid-base neutralization
$\mathrm{CH}_{3} \mathrm{COOH}(\mathrm{aq})+\mathrm{NaOH}(\mathrm{aq}) \stackrel{\mathrm{NaCH}_{3} \mathrm{COO}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)}$
When we add $20.00 \mathrm{~mL}$ of $0.625 \mathrm{M} \mathrm{NaOH}$ at $21.400^{\circ} \mathrm{C}$
to $30.00 \mathrm{~mL}$ of $0.500 \mathrm{MCH}_{3} \mathrm{COOH}$ already in the calorimeter at the same temperature, the resulting temperature is observed to be $24.347^{\circ} \mathrm{C}$. The heat capacity of the calorimeter has previously been determined to be $27.8 \mathrm{~J} /{ }^{\circ} \mathrm{C}$. Assume that the specific heat of the mixture is the same as that of water, $4.184 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$, and that the density of the mixture is $1.02 \mathrm{~g} / \mathrm{mL}$. (a) Calculate the amount of heat given off in the reaction. (b) Determine $\Delta H$ for the reaction under the conditions of the experiment.

Anthony Han
Anthony Han
Numerade Educator
03:45

Problem 66

In a bomb calorimeter compartment surrounded by $945 \mathrm{~g}$ of water, the combustion of $1.048 \mathrm{~g}$ of benzene, $\mathrm{C}_{6} \mathrm{H}_{6}(\ell)$, raised the temperature of the water from $23.640^{\circ} \mathrm{C}$ to $32.692^{\circ} \mathrm{C}$. The heat capacity of the calorimeter is $891 \mathrm{~J} /{ }^{\circ} \mathrm{C}$. (a) Write the balanced equation for the combustion reaction, assuming that $\mathrm{CO}_{2}(\mathrm{~g})$ and $\mathrm{H}_{2} \mathrm{O}(\ell)$ are the only products. (b) Use the calorimetric data to calculate $\Delta E$ for the combustion of benzene in $\mathrm{kJ} / \mathrm{g}$ and in $\mathrm{kJ} / \mathrm{mol}$.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
02:46

Problem 67

A $2.00-\mathrm{g}$ sample of hydrazine, $\mathrm{N}_{2} \mathrm{H}_{4}$, is burned in a bomb calorimeter that contains $6.40 \times 10^{3} \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}$, and the temperature increases from $25.00^{\circ} \mathrm{C}$ to $26.17^{\circ} \mathrm{C}$. The heat capacity of the calorimeter is $3.76 \mathrm{~kJ} /{ }^{\circ} \mathrm{C}$. Calculate $\Delta E$ for the comhustion of $\mathrm{N}_{2} \mathrm{H}$, in $\mathrm{kJ} / \mathrm{g}$ and in $\mathrm{kJ} / \mathrm{mol}$.

Aadit Sharma
Aadit Sharma
Numerade Educator
02:39

Problem 68

A strip of magnesium metal having a mass of $1.22 \mathrm{~g}$ dissolves in $100 . \mathrm{mL}$ of $6.02 M \mathrm{HCl}$, which has a specific gravity of $1.10$. The hydrochloric acid is initially at $23.0^{\circ} \mathrm{C}$, and the resulting solution reaches a final temperature of $45.5^{\circ} \mathrm{C}$. The heat capacity of the calorimeter in which the reaction occurs is $562 \mathrm{~J} /{ }^{\circ} \mathrm{C}$. Calculate $\Delta H$ for the reaction under the conditions of the experiment, assuming the specific heat of the final solution is the same as that for water, $4.184 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$
$$\mathrm{Mg}(\mathrm{s})+2 \mathrm{HCl}(\mathrm{aq}) \longrightarrow \mathrm{MgCl}_{2}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g})$$

Aadit Sharma
Aadit Sharma
Numerade Educator
01:55

Problem 69

When $3.16 \mathrm{~g}$ of salicylic acid, $\mathrm{C}_{7} \mathrm{H}_{6} \mathrm{O}_{3}$, is burned in a bomb calorimeter containing $5.00 \mathrm{~kg}$ of water originally at $23.00^{\circ} \mathrm{C}, 69.3 \mathrm{~kJ}$ of heat is evolved. The calorimeter constant is $3255 \mathrm{~J} /{ }^{\circ} \mathrm{C}$. Calculate the final temperature.

Anthony Han
Anthony Han
Numerade Educator
02:34

Problem 70

A $6.620-\mathrm{g}$ sample of decane, $\mathrm{C}_{10} \mathrm{H}_{22}(\ell)$, was burned in a bomb calorimeter whose heat capacity had been determined to be $2.45 \mathrm{~kJ} /{ }^{\circ} \mathrm{C}$. The temperature of $1250.0 \mathrm{~g}$ of water rose from $24.6^{\circ} \mathrm{C}$ to $26.4^{\circ} \mathrm{C}$. Calculate $\Delta E$ for the reaction in joules per gram of decane and in kilojoules per mole of decane. The specific heat of water is $4.184 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$.

Aadit Sharma
Aadit Sharma
Numerade Educator
03:32

Problem 71

A nutritionist determines the caloric value of a $10.00-\mathrm{g}$ sample of beef fat by burning it in a bomb calorimeter. The calorimeter held $2.500 \mathrm{~kg}$ of water, the heat capacity of the bomb is $1.360 \mathrm{~kJ} /{ }^{\circ} \mathrm{C}$, and the temperature of the calorimeter increased from $25.0^{\circ} \mathrm{C}$ to $56.9^{\circ} \mathrm{C} .$ (a) Calculate the number of joules released per gram of beef fat. (b) One nutritional Calorie is $1 \mathrm{kcal}$ or 4184 joules. What is the dietary, caloric value of beef fat, in nutritional Calories per gram?

Anthony Han
Anthony Han
Numerade Educator
01:21

Problem 72

(a) What are the sign conventions for $q$, the amount of heat added to or removed from a system? (b) What are the sign conventions for $w$, the amount of work done on or by a system?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:11

Problem 73

What happens to $\Delta E$ for a system during a process in which (a) $q<0$ and $w<0$, (b) $q=0$ and $w>0$, and
(c) $q>0$ and $w<0$.

Anthony Han
Anthony Han
Numerade Educator
01:40

Problem 74

Ammonium nitrate, commonly used as a fertilizer, decomposes explosively:
$$2 \mathrm{NH}_{4} \mathrm{NO}_{3}(\mathrm{~s}) \longrightarrow 2 \mathrm{~N}_{2}(\mathrm{~g})+4 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{~g})$$
(This reaction has been responsible for several major explosions.) For this reaction:
(a) Is work $(w)$ positive, negative, or 0 ?
(b) If $w<0$, is work done on the system or by the system?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:29

Problem 75

A system receives 96 J of electrical work, performs 257 J of pressure-volume work, and releases $175 \mathrm{~J}$ of heat. What is the change in internal energy of the system?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:18

Problem 76

A system receives 96 J of electrical work, performs 257 J of pressure-volume work, and releases $175 \mathrm{~J}$ of heat. What is the change in internal energy of the system?

Aadit Sharma
Aadit Sharma
Numerade Educator
02:15

Problem 77

For each of the following chemical and physical changes carried out at constant pressure, state whether work is done by the system on the surroundings or by the surroundings on the system, or whether the amount of work is negligible.
(a) $\mathrm{C}_{6} \mathrm{H}_{6}(\ell) \longrightarrow \mathrm{C}_{6} \mathrm{H}_{6}(\mathrm{~g})$
(b) $\frac{1}{2} \mathrm{~N}_{2}(\mathrm{~g})+{ }_{2}^{3} \mathrm{H}_{2}(\mathrm{~g}) \longrightarrow \mathrm{NH}_{3}(\mathrm{~g})$
(c) $\mathrm{SiO}_{2}(\mathrm{~s})+3 \mathrm{C}(\mathrm{s}) \longrightarrow \mathrm{SiC}(\mathrm{s})+2 \mathrm{CO}(\mathrm{g})$

Aadit Sharma
Aadit Sharma
Numerade Educator
02:04

Problem 78

Repeat Exercise 77 for (a) $2 \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{SO}_{3}(\mathrm{~g})$
(b) $\mathrm{CaCO}_{3}(\mathrm{~s}) \longrightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g})$
(c) $\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{CaCO}_{3}(\mathrm{~s}) \stackrel{\mathrm{Ca}^{2+}(\mathrm{aq})}+2 \mathrm{HCO}_{3}^{-}(\mathrm{aq})$

Aadit Sharma
Aadit Sharma
Numerade Educator
03:16

Problem 79

Assuming that the gases are ideal, calculate the amount of work done (in joules) in each of the following reactions. In each case, is the work done on or by the system? (a) $\mathrm{A}$ reaction in the Mond process for purifying nickel that involves formation of the gas nickel(0) tetracarbonyl at $50-100^{\circ} \mathrm{C}$. Assume one mole of nickel is used and a constant temperature of $75^{\circ} \mathrm{C}$ is maintained.
$$\mathrm{Ni}(\mathrm{s})+4 \mathrm{CO}(\mathrm{g}) \longrightarrow \mathrm{Ni}(\mathrm{CO})_{4}(\mathrm{~g})$$
(b) The conversion of one mole of brown nitrogen dioxide into colorless dinitrogen tetroxide at $8.0^{\circ} \mathrm{C}$.
$$2 \mathrm{NO}_{2}(\mathrm{~g}) \longrightarrow \mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{~g})$$

Aadit Sharma
Aadit Sharma
Numerade Educator
01:37

Problem 80

Assuming that the gases are ideal, calculate the amount of work done (in joules) in each of the following reactions. In each case, is the work done on or $b$ y the system? (a) The oxidation of one mole of $\mathrm{HCl}(\mathrm{g})$ at $200^{\circ} \mathrm{C}$.
$$4 \mathrm{HCl}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{Cl}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$$
(b) The decomposition of one mole of nitric oxide (an air pollutant) at $300 .{ }^{\circ} \mathrm{C}$.
$$2 \mathrm{NO}(\mathrm{g}) \longrightarrow \mathrm{N}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g})$$

Aadit Sharma
Aadit Sharma
Numerade Educator
05:33

Problem 81

When an ideal gas expands at constant tempemature, there is no change in molecular kinetic energy (kinetic energy is proportional to temperature), and there is no change in potential energy due to intermolecular attractions (these are zero for an ideal gas). Thus for the isothermal (constant temperature) expansion of an ideal gas, $\Delta E=0$. Suppose we allow an ideal gas to expand isothermally from $2.50 \mathrm{~L}$ to $5.50 \mathrm{~L}$ in two steps: (a) against a constant external pressure of $3.50$ atm until equilibrium is reached, then (b) against a constant external pressure of $2.50 \mathrm{~atm}$ until equilibrium is reached. Calculate $q$ and $w$ for this two-step expansion.

Ronald Prasad
Ronald Prasad
Numerade Educator
01:26

Problem 82

A car uses gasoline as a fuel. Describe the burning of the fuel in terms of chemical and physical changes. Relate your answer to the Second Law of Thermodynamics.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:30

Problem 83

State the Second Law of Thermodynamics. Why can't we use $\Delta S_{\text {univ }}$ directly as a measure of the spontaneity of a reaction?

Anthony Han
Anthony Han
Numerade Educator
00:53

Problem 84

State the Third Law of Thermodynamics. What does it mean?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:16

Problem 85

Explain why $\Delta S$ may be referred to as a contributor to spontaneity.

Anthony Han
Anthony Han
Numerade Educator
01:28

Problem 86

Suppose you flip a coin. (a) What is the probability that it will come up heads? (b) What is the probability that it will come up heads two times in a row? (c) What is the probability that it will come up heads ten times in a row?

Anthony Han
Anthony Han
Numerade Educator
01:34

Problem 87

Consider two equal-sized flasks connected as shown in the figure.
(a) Suppose you put one molecule inside. What is the probability that the molecule will be in flask A? What is the probability that it will be in flask $\mathrm{B}$ ?
(b) If you put 100 molecules into the two-flask system, what is the most likely distribution of molecules? Which distribution corresponds to the highest entropy?
(c) Write a mathematical expression for the probability that all 100 molecules in part (b) will be in flask $\mathrm{A}$. (You do not need to evaluate this expression.)

Aadit Sharma
Aadit Sharma
Numerade Educator
01:46

Problem 88

Suppose you have two identical red molecules labeled $\mathrm{A}$ and $\mathrm{B}$, and two identical blue molecules labeled $\mathrm{C}$ and
D. Draw a simple two-flask diagram as in the figure for Exercise 87, and then draw all possible arrangements of the four molecules in the two flasks.
(a) How many different arrangements are possible?
(b) How many of the arrangements have a mixture of unlike molecules in at least one of the flasks? (c) What is the probability that at least one of the flasks contains a mixture of unlike molecules?
(d) What is the probability that the gases are not mixed (each flask contains only like molecules)?

Aadit Sharma
Aadit Sharma
Numerade Educator
03:18

Problem 89

For each process, tell whether the entropy change of the system is positive or negative. (a) Water vapor (the system) condenses as droplets on a cold windowpane.
(b) Water boils. (c) A can of carbonated beverage loses its fizz. (Consider the beverage, but not the can, as the system. What happens to the entropy of the dissolved gas?)

Anthony Han
Anthony Han
Numerade Educator
02:16

Problem 90

For each process, tell whether the entropy change of the system is positive or negative. (a) A glassblower heats glass (the system) to its softening temperature. (b) $\mathrm{A}$ teaspoon of sugar dissolves in a cup of coffee. (The system consists of both sugar and coffee.) (c) Calcium carbonate precipitates out of water in a cave to form stalactites and stalagmites. (Consider only the calcium carbonate to be the system.)

Anthony Han
Anthony Han
Numerade Educator
01:32

Problem 91

For each of the following processes, tell whether the entropy of the universe increases, decreases, or remains constant: (a) melting one mole of ice to water at $0 .{ }^{\circ} \mathrm{C}$;
(b) freezing one mole of water to ice at $0 .{ }^{\circ} \mathrm{C} ;(\mathrm{c})$ freezing one mole of water to ice at $-15^{\circ} \mathrm{C} ;$ (d) freezing one mole of water to ice at $0 .{ }^{\circ} \mathrm{C}$ and then cooling it to $-15^{\circ} \mathrm{C}$.

Aadit Sharma
Aadit Sharma
Numerade Educator
03:08

Problem 92

In which of the following changes is there an increase in entropy?
(a) The freezing of water
(b) The condensation of steam
(c) The sublimation of dry ice, solid $\mathrm{CO}_{2}$
(d) The separation of salts and pure water from seawater

Anthony Han
Anthony Han
Numerade Educator
01:33

Problem 93

When solid sodium chloride is cooled from $25^{\circ} \mathrm{C}$ to $0 .{ }^{\circ} \mathrm{C}$, the entropy change is $-4.4 \mathrm{~J} / \mathrm{mol} \cdot \mathrm{K}$. Is this an
increase or decrease in randomness? Explain this entropy change in terms of what happens in the solid at the molecular level.

Aadit Sharma
Aadit Sharma
Numerade Educator
02:00

Problem 94

When a one-mole sample of argon gas at $0 .{ }^{\circ} \mathrm{C}$ is compressed to one half its original volume, the entropy change is $-5.76 \mathrm{~J} / \mathrm{mol} \cdot \mathrm{K}$. Is this an increase or a decrease in dispersal of energy? Explain this entropy change in terms of what happens in the gas at the molecular level.

Anthony Han
Anthony Han
Numerade Educator
03:20

Problem 95

Which of the following processes are accompanied by an increase in entropy of the system? (No calculation is necessary.) (a) Dry ice, $\mathrm{CO}_{2}(\mathrm{~s})$, sublimes at $-78^{\circ} \mathrm{C}$ and then the resulting $\mathrm{CO}_{2}(\mathrm{~g})$ is warmed to $0^{\circ} \mathrm{C}$. (b) Water vapor forms snowflakes, $\mathrm{H}_{2} \mathrm{O}(\mathrm{s}) .$ (c) Iodine sublimes, $\mathrm{I}_{2}(\mathrm{~s}) \longrightarrow \mathrm{I}_{2}(\mathrm{~g})$
(d) White silver sulfate, $\mathrm{Ag}_{2} \mathrm{SO}_{4}$ precipitates from a solution containing silver ions and sulfate ions. (e) A partition is removed to allow two gases to mix.

Aadit Sharma
Aadit Sharma
Numerade Educator
04:15

Problem 96

Which of the following processes are accompanied by an increase in entropy of the system? (No calculation is necessary.) (a) Solid $\mathrm{NaCl}$ is dissolved in water at room temperature. (b) A saturated solution of $\mathrm{NaCl}$ is cooled, causing some solid $\mathrm{NaCl}$ to precipitate. (c) Water freezes.
(d) Carbon tetrachloride, $\mathrm{CCl}_{4}$, evaporates. (e) The reaction $\mathrm{PCl}_{5}(\mathrm{~g}) \longrightarrow \mathrm{PCl}_{3}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g})$ occurs. (f) The
reaction $\mathrm{PCl}_{3}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \longrightarrow \mathrm{PCl}_{5}(\mathrm{~g})$ occurs.

Anthony Han
Anthony Han
Numerade Educator
03:17

Problem 97

For each pair, tell which would have the greater absolute entropy per mole (standard molar entropy) at the same temperature. Give the reasons for your choice.
(a) $\mathrm{NaCl}(\mathrm{s})$ or $\mathrm{CaO}(\mathrm{s})$
(b) $\mathrm{Cl}_{2}(\mathrm{~g})$ or $\mathrm{P}_{4}(\mathrm{~g})$
(c) $\mathrm{AsH}_{3}(\mathrm{~g})$ or $\mathrm{Kr}(\mathrm{g})$
(d) $\mathrm{NH}_{4} \mathrm{NO}_{3}(\mathrm{~s})$ or $\mathrm{NH}_{4} \mathrm{NO}_{3}(\mathrm{aq})$
(e) $\mathrm{Ga}(\mathrm{s})$ or $\mathrm{Ga}(\ell)$

Anthony Han
Anthony Han
Numerade Educator
03:03

Problem 98

For each pair, tell which would have the greater absolute entropy per mole (standard molar entropy) at the same temperature. Give the reasons for your choice.
(a) $\mathrm{NaF}(\mathrm{s})$ or $\mathrm{MgO}(\mathrm{s})$
(b) $\mathrm{Au}(\mathrm{s})$ or $\mathrm{Hg}(\ell)$
(c) $\mathrm{H}_{2} \mathrm{O}(\mathrm{g})$ or $\mathrm{H}_{2} \mathrm{~S}(\mathrm{~g})$
(d) $\mathrm{CH}_{3} \mathrm{OH}(\ell)$ or $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\ell)$
(e) $\mathrm{NaOH}(\mathrm{s})$ or $\mathrm{NaOH}(\mathrm{aq})$

Anthony Han
Anthony Han
Numerade Educator
02:06

Problem 99

(a) For which change would the entropy change by the greatest amount: (i) condensation of one mole of water vapor to make one mole of liquid water, or (ii) deposition of one mole of water vapor to make one mole of ice?
(b) Would the entropy changes for the changes in (a) be positive or negative? Give reasons for your answer.

Aadit Sharma
Aadit Sharma
Numerade Educator
03:04

Problem 100

Without doing a calculation predict whether the entropy change will be positive or negative when each reaction occurs in the direction it is written.
(a) $\mathrm{C}_{3} \mathrm{H}_{6}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g}) \longrightarrow \mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g})$
(b) $\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{NH}_{3}(\mathrm{~g})$
(c) $\mathrm{CaCO}_{3}(\mathrm{~s}) \longrightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g})$
(d) $\mathrm{Mg}(\mathrm{s})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{MgO}(\mathrm{s})$
(e) $\mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq}) \longrightarrow \mathrm{AgCl}(\mathrm{s})$

Anthony Han
Anthony Han
Numerade Educator
03:20

Problem 101

Without doing a calculation predict whether the entropy change will be positive or negative when each reaction occurs in the direction it is written.
(a) $\mathrm{CH}_{3} \mathrm{OH}(\ell)+\frac{3}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$
(b) $\mathrm{Br}_{2}(\ell)+\mathrm{H}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{HBr}(\mathrm{g})$
(c) $\mathrm{Na}(\mathrm{s})+\frac{1}{2} \mathrm{~F}_{2}(\mathrm{~g}) \longrightarrow \mathrm{NaF}(\mathrm{s})$
(d) $\mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CH}_{3} \mathrm{OH}(\ell)$
(e) $\mathrm{NH}_{3}(\mathrm{~g}) \longrightarrow \mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g})$

Anthony Han
Anthony Han
Numerade Educator
03:34

Problem 102

Consider the boiling of a pure liquid at constant pressure. Is each of the following greater than, less than, or equal to zero? (a) $\Delta S_{\text {sys }}$; (b) $\Delta H_{\text {sys }}$; (c) $\Delta T_{\text {sys }}$.

Anthony Han
Anthony Han
Numerade Educator
01:33

Problem 103

Use $S^{0}$ data from Appendix $\mathrm{K}$ to calculate the value of $\Delta S_{298}^{0}$ for each of the following reactions. Compare the signs and magnitudes for these $\Delta S_{298}^{0}$ values and explain your observations.
(a) $2 \mathrm{NO}(\mathrm{g})+\mathrm{H}_{2}(\mathrm{~g}) \longrightarrow \mathrm{N}_{2} \mathrm{O}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g})$
(b) $2 \mathrm{~N}_{2} \mathrm{O}_{5}(\mathrm{~g}) \longrightarrow 4 \mathrm{NO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g})$
(c) $\mathrm{NH}_{4} \mathrm{NO}_{3}(\mathrm{~s}) \longrightarrow \mathrm{N}_{2} \mathrm{O}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$

David Collins
David Collins
Numerade Educator
01:42

Problem 104

Use $S^{0}$ data from Appendix $K$ to calculate the value of $\Delta S_{298}^{0}$ for each of the following reactions. Compare the signs and magnitudes for these $\Delta S_{298}^{0}$ values and explain your observations.
(a) $4 \mathrm{HCl}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{Cl}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$
(b) $\mathrm{PCl}_{3}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \longrightarrow \mathrm{PCl}_{5}(\mathrm{~g})$
(c) $2 \mathrm{~N}_{2} \mathrm{O}(\mathrm{g}) \longrightarrow 2 \mathrm{~N}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g})$

David Collins
David Collins
Numerade Educator
03:54

Problem 105

(a) What are the two factors that favor spontaneity of a process? (b) What is Gibbs free energy? What is change in Gibbs free energy? (c) Most spontaneous reactions are exothermic, but some are not. Explain. (d) Explain how the signs and magnitudes of $\Delta H$ and $\Delta S$ are related to the spontaneity of a process.

Aadit Sharma
Aadit Sharma
Numerade Educator
03:03

Problem 106

Which of the following conditions would predict a process that is (a) always spontaneous, (b) always nonspontaneous, or (c) spontaneous or nonspontaneous depending on the temperature and magnitudes of $\Delta H$ and $\Delta S$ ? (i) $\Delta H>0$, $\Delta S>0 ;$ (ii) $\Delta H>0, \Delta S<0 ;$ (iii) $\Delta H<0, \Delta S>0 ;$
(iv) $\Delta H<0, \Delta S>0$

Anthony Han
Anthony Han
Numerade Educator
01:28

Problem 107

Calculate $\Delta G^{\circ}$ at $45^{\circ} \mathrm{C}$ for reactions for which
(a) $\Delta H^{\circ}=293 \mathrm{~kJ} ; \Delta S^{\circ}=-695 \mathrm{~J} / \mathrm{K}$.
(b) $\Delta H^{\circ}=-1137 \mathrm{~kJ} ; \Delta S^{\circ}=0.496 \mathrm{~kJ} / \mathrm{K}$.
(c) $\Delta H^{\circ}=-86.6 \mathrm{~kJ} ; \Delta S^{\circ}=-382 \mathrm{~J} / \mathrm{K}$.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:06

Problem 108

Evaluate $\Delta S^{0}$ at $25^{\circ} \mathrm{C}$ and 1 atm for the reaction:

Aadit Sharma
Aadit Sharma
Numerade Educator
01:29

Problem 109

The standard Gibbs free energy of formation is $-286.06$ $\mathrm{kJ} / \mathrm{mol}$ for NaI(s), $-261.90 \mathrm{~kJ} / \mathrm{mol}$ for $\mathrm{Na}^{+}(\mathrm{aq})$, and $-51.57$
$\mathrm{kJ} / \mathrm{mol}$ for $\mathrm{I}^{-}(\mathrm{aq})$ at $25^{\circ} \mathrm{C}$. Calculate $\Delta G^{0}$ for the reaction
$$\mathrm{NaI}(\mathrm{s}) \stackrel{\mathrm{H}_{2} \mathrm{O}}{\longrightarrow} \mathrm{Na}^{+}(\mathrm{aq})+\mathrm{I}^{-}(\mathrm{aq})$$

Anthony Han
Anthony Han
Numerade Educator
03:23

Problem 110

Use the following equations to find $\Delta G_{\mathrm{f}}^{0}$ for $\mathrm{HBr}(\mathrm{g})$ at $25^{\circ} \mathrm{C} .$
$\mathrm{Br}_{2}(\ell) \longrightarrow \mathrm{Br}_{2}(\mathrm{~g})$
$\Delta G^{0}=3.14 \mathrm{~kJ} / \mathrm{mol}$
$\mathrm{HBr}(\mathrm{g}) \longrightarrow \mathrm{H}(\mathrm{g})+\mathrm{Br}(\mathrm{g}) \quad \Delta G^{0}=339.09 \mathrm{~kJ} / \mathrm{mol}$
$\mathrm{Br}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{Br}(\mathrm{g})$
$\Delta G^{0}=161.7 \mathrm{~kJ} / \mathrm{mol}$
$\mathrm{H}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{H}(\mathrm{g})$
$\Delta G^{0}=406.494 \mathrm{~kJ} / \mathrm{mol}$

Aadit Sharma
Aadit Sharma
Numerade Educator
01:40

Problem 111

Use values of standard free energy of formation, $\Delta G_{f}^{0}$, from Appendix $\mathrm{K}$ to calculate the standard free energy change for each of the following reactions at $25^{\circ} \mathrm{C}$ and $1 \mathrm{~atm}$.
(a) $3 \mathrm{NO}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow 2 \mathrm{HNO}_{3}(\ell)+\mathrm{NO}(\mathrm{g})$
(b) $\mathrm{SnO}_{2}(\mathrm{~s})+2 \mathrm{CO}(\mathrm{g}) \longrightarrow 2 \mathrm{CO}_{2}(\mathrm{~g})+\mathrm{Sn}(\mathrm{s})$
(c) $2 \mathrm{Na}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow 2 \mathrm{NaOH}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g})$

David Collins
David Collins
Numerade Educator
02:38

Problem 112

Make the same calculations as in Exercise 111 , using values of standard enthalpy of formation and absolute entropy instead of values of $\Delta G_{f}^{0}$

Arun Bana
Arun Bana
Numerade Educator
04:04

Problem 113

Calculate $\Delta G^{0}$ at $298 \mathrm{~K}$ for the reaction:
$$\mathrm{P}_{4} \mathrm{O}_{10}(\mathrm{~s})+6 \mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow 4 \mathrm{H}_{3} \mathrm{PO}_{4}(\mathrm{~s})$$
$\Delta H_{\mathrm{f}}^{0}, \mathrm{~kJ} / \mathrm{mol}:$
$$\begin{array}{rrr}-2984 & -285.8 & -1281 \\228.9 & 69.91 & 110.5\end{array}$$
$S^{0}, J / m o l \cdot K$

Anthony Han
Anthony Han
Numerade Educator
01:58

Problem 114

Are the following statements true or false? Justify your answers. (a) An exothermic reaction is always spontaneous.
(b) If $\Delta H$ and $\Delta S$ are both positive, then $\Delta G$ will decrease when the temperature increases. (c) A reaction for which $\Delta S_{\text {sss }}$ is positive is spontaneous.

Aadit Sharma
Aadit Sharma
Numerade Educator
04:21

Problem 115

For the reaction
$$\mathrm{C}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{~g})$$
$\Delta H^{0}=-393.51 \mathrm{~kJ} / \mathrm{mol}$ and $\Delta S^{0}=2.86 \mathrm{~J} / \mathrm{mol} \cdot \mathrm{K}$ at
$25^{\circ} \mathrm{C} .$ (a) Does this reaction become more or less favorable as the temperature increases? (b) For the reaction
$$\mathrm{C}(\mathrm{s})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}(\mathrm{g})$$
$\Delta H^{0}=-110.52 \mathrm{~kJ} / \mathrm{mol}$ and $\Delta S^{0}=89.36 \mathrm{~J} / \mathrm{mol} \cdot \mathrm{K}$ at
$25^{\circ} \mathrm{C}$. Does this reaction become more or less favorable as the temperature increases? (c) Compare the temperature dependencies of these reactions.

Anthony Han
Anthony Han
Numerade Educator
01:50

Problem 116

(a) Calculate $\Delta H^{0}, \Delta G^{0}$, and $\Delta S^{0}$ for the reaction
$2 \mathrm{H}_{2} \mathrm{O}_{2}(\ell) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{O}_{2}(\mathrm{~g})$ at $25^{\circ} \mathrm{C} .$
(b) Is there any temperature at which $\mathrm{H}_{2} \mathrm{O}_{2}(\ell)$ is stable at 1 atm?

David Collins
David Collins
Numerade Educator
01:39

Problem 117

When is it true that $\Delta S=\frac{\Delta H}{T}$ ?

Anthony Han
Anthony Han
Numerade Educator
02:34

Problem 118

Dissociation reactions are those in which molecules break apart. Why do high temperatures favor the spontaneity of most dissociation reactions?

Anthony Han
Anthony Han
Numerade Educator
09:28

Problem 119

Estimate the temperature range over which each of the following standard reactions is spontaneous.
(a) $2 \mathrm{Al}(\mathrm{s})+3 \mathrm{Cl}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{AlCl}_{3}(\mathrm{~s})$
(b) $2 \mathrm{NOCl}(\mathrm{g}) \longrightarrow 2 \mathrm{NO}(\mathrm{g})+\mathrm{Cl}_{2}(\mathrm{~g})$
(c) $4 \mathrm{NO}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \longrightarrow 4 \mathrm{NH}_{3}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g})$
(d) $2 \mathrm{PH}_{3}(\mathrm{~g}) \longrightarrow 3 \mathrm{H}_{2}(\mathrm{~g})+2 \mathrm{P}(\mathrm{g})$

Katie Miller
Katie Miller
Numerade Educator
02:08

Problem 120

Estimate the temperature range over which each of the following standard reactions is spontaneous. (a) The reaction by which sulfuric acid droplets from polluted air convert water-insoluble limestone or marble (calcium carbonate) to slightly soluble calcium sulfate, which is slowly washed away by rain:
$\mathrm{CaCO}_{3}(\mathrm{~s})+\mathrm{H}_{2} \mathrm{SO}_{4}(\ell) \longrightarrow \mathrm{CaSO}_{4}(\mathrm{~s})+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{CO}_{2}(\mathrm{~g}$
(b) The reaction by which Antoine Lavoisier achieved the first laboratory preparation of oxygen in the late eighteenth century: the thermal decomposition of the red-orange powder, mercury(II) oxide, to oxygen and the silvery liquid metal, mercury:
$$
2 \mathrm{HgO}(\mathrm{s}) \longrightarrow 2 \mathrm{Hg}(\ell)+\mathrm{O}_{2}(\mathrm{~g})
$$(c) The reaction of coke (carbon) with carbon dioxide to form the reducing agent, carbon monoxide, which is used to reduce some metal ores to metals:$$
\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{C}(\mathrm{s}) \longrightarrow 2 \mathrm{CO}(\mathrm{g})
$$(d) The reverse of the reaction by which iron rusts:
$$2 \mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{~s}) \longrightarrow 4 \mathrm{Fe}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{~g})$$

Manik Pulyani
Manik Pulyani
Numerade Educator
01:11

Problem 121

Estimate the normal boiling point of pentacarbonyliron(0), $\mathrm{Fe}(\mathrm{CO})_{5}$, at 1 atm pressure, using Appendix $\mathrm{K}$

David Collins
David Collins
Numerade Educator
01:49

Problem 122

(a) Estimate the normal boiling point of water, at 1 atm pressure, using Appendix $\mathrm{K}$. (b) Compare the temperature obtained with the known boiling point of water. Can you explain the discrepancy?

David Collins
David Collins
Numerade Educator
01:18

Problem 123

Sublimation and subsequent deposition onto a cold surface are a common method of purification of $\mathrm{I}_{2}$ and other solids that sublime readily. Estimate the sublimation temperature (solid to vapor) of the dark violet solid iodine, $\mathrm{I}_{2}$, at 1 atm pressure, using the data of Appendix $\mathrm{K}$.

David Collins
David Collins
Numerade Educator
01:27

Problem 124

Some metal oxides can be decomposed to the metal and oxygen under reasonable conditions. Is the decomposition of nickel(II) oxide product-favored at $25^{\circ} \mathrm{C}$ ?
$$2 \mathrm{NiO}(\mathrm{s}) \longrightarrow 2 \mathrm{Ni}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g})$$
If not, can it become so if the temperature is raised? At what temperature does the reaction become product-favored?

Sriparna Bhattacharjee
Sriparna Bhattacharjee
Numerade Educator
09:28

Problem 125

Calculate $\Delta H^{\circ}$ and $\Delta S^{\circ}$ for the reaction of tin(IV) oxide with carbon.
$$\mathrm{SnO}_{2}(\mathrm{~s})+\mathrm{C}(\mathrm{s}) \longrightarrow \mathrm{Sn}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g})$$
(a) Is the reaction spontaneous under standard conditions at $298 \mathrm{~K} ?$
(b) Is the reaction predicted to be spontaneous at higher temperatures?

Temi Ajayi
Temi Ajayi
Numerade Educator
01:56

Problem 126

Calculate $\Delta S^{\circ}$ system at $25^{\circ} \mathrm{C}$ for the reaction
$$\mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH(\ell)$$
Can you tell from the result of this calculation whether this reaction is product-favored? If you cannot tell, what additional information do you need? Obtain that information and determine whether the reaction is product-favored.

Nicole Mabante
Nicole Mabante
Numerade Educator
02:05

Problem 127

An ice calorimeter, shown below, can be used to measure the amount of heat released or absorbed by a reaction that is carried out at a constant temperature of $0 .{ }^{\circ} \mathrm{C}$. If heat is transferred from the system to the bath, some of the ice melts. A given mass of liquid water has a smaller volume than the same mass of ice, so the total volume of the ice and water mixture decreases. Measuring the volume decrease using the scale at the left indicates the amount of heat released by the reacting system. As long as some ice remains in the bath, the temperature remains at $0 .{ }^{\circ} \mathrm{C}$. In Example $15-2$ we saw that the reaction
$\mathrm{CuSO}_{4}(\mathrm{aq})+2 \mathrm{NaOH}(\mathrm{aq}) \longrightarrow \mathrm{Cu}(\mathrm{OH})_{2}(\mathrm{~s})+\mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq})$
releases $846 \mathrm{~J}$ of heat at constant temperature and pressure when $50.0 \mathrm{~mL}$ of $0.400 \mathrm{M} \mathrm{CuSO}_{4}$ solution and $50.0 \mathrm{~mL}$
of $0.600 \mathrm{M} \mathrm{NaOH}$ solution are allowed to react. (Because no gases are involved in the reaction, the volume change of the reaction mixture is negligible.) Calculate the change in volume of the ice and water mixture that would be observed if we carried out the same experiment in an ice calorimeter. The density of $\mathrm{H}_{2} \mathrm{O}(\ell)$ at $0 .{ }^{\circ} \mathrm{C}$ is $0.99987$ $\mathrm{g} / \mathrm{mL}$ and that of ice is $0.917 \mathrm{~g} / \mathrm{mL} .$ The heat of fusion of ice at $0^{\circ} \mathrm{C}$ is $334 \mathrm{~J} / \mathrm{g}$.

Aadit Sharma
Aadit Sharma
Numerade Educator
02:00

Problem 128

It is difficult to prepare many compounds directly from their elements, so $\Delta H_{\mathrm{f}}^{0}$ values for these compounds cannot be measured directly. For many organic compounds, it is easier to measure the standard enthalpy of combustion by reaction of the compound with excess $\mathrm{O}_{2}(\mathrm{~g})$ to form $\mathrm{CO}_{2}(\mathrm{~g})$ and $\mathrm{H}_{2} \mathrm{O}(\ell) .$ From the following standard enthalpies of combustion at $25^{\circ} \mathrm{C}$, determine $\Delta H_{\mathrm{f}}^{0}$ for the compound. (a) cyclohexane, $\mathrm{C}_{6} \mathrm{H}_{12}(\ell)$, a useful organic solvent: $\Delta H_{\text {cumbustion }}^{0}=-3920 . \mathrm{kJ} / \mathrm{mol} ;$ (b) phenol, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}(\mathrm{s})$, used as a disinfectant and in the production of thermo-setting plastics: $\Delta H_{\text {combusting }}^{0}=-3053 \mathrm{~kJ} / \mathrm{mol}$.

Manik Pulyani
Manik Pulyani
Numerade Educator
02:46

Problem 129

Standard entropy changes cannot be measured directly in the laboratory. They are calculated from experimentally obtained values of $\Delta G^{0}$ and $\Delta H^{0} .$ From the data given here, calcuiate $\Delta S^{0}$ at $298 \mathrm{~K}$ for each of the following reactions.
(a) $\mathrm{OF}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{O}_{2}(\mathrm{~g})+2 \mathrm{HF}(\mathrm{g})$
$\Delta H^{0}=-323.2 \mathrm{~kJ} / \mathrm{mol}$
$\Delta G^{0}=-358.4 \mathrm{~kJ} / \mathrm{mol}$
(b) $\mathrm{CaC}_{2}(\mathrm{~s})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow \mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{~s})+\mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{~g})$
$\Delta H^{0}=-125.4 \mathrm{~kJ} / \mathrm{mol}$
$\Delta G^{0}=-145.4 \mathrm{~kJ} / \mathrm{mol}$
(c) $\mathrm{CaO}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow \mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{aq})$
$\Delta H^{0}=81.5 \mathrm{~kJ} / \mathrm{mol}$
$\Delta G^{0}=-26.20 \mathrm{~kJ} / \mathrm{mol}$

Anthony Han
Anthony Han
Numerade Educator
01:24

Problem 130

Calculate $q, w$, and $\Delta E$ for the vaporization of $12.5 \mathrm{~g}$ of liquid ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ at $1.00 \mathrm{~atm}$ at $78.0^{\circ} \mathrm{C}$, to
form gaseous ethanol at $1.00 \mathrm{~atm}$ at $78.0^{\circ} \mathrm{C}$. Make the following simplifying assumptions: (a) the density of liquid ethanol at $78.0^{\circ} \mathrm{C}$ is $0.789 \mathrm{~g} / \mathrm{mL}$, and $(\mathrm{b})$ gaseous ethanol is adequately described by the ideal gas equation. The heat of vaporization of ethanol is $855 \mathrm{~J} / \mathrm{g}$.

Aadit Sharma
Aadit Sharma
Numerade Educator
03:11

Problem 131

We add $0.100 \mathrm{~g}$ of $\mathrm{CaO}(\mathrm{s})$ to $125 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}$ at $23.6^{\circ} \mathrm{C}$ in
a coffee-cup calorimeter. The following reaction occurs. What will be the final temperature of the solution?
$\mathrm{CaO}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow \mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{aq})$
$\Delta H^{0}=81.5 \mathrm{~kJ} / \mathrm{mol} \mathrm{rxn}$

Shubham Kanungo
Shubham Kanungo
Numerade Educator
07:07

Problem 132

(a) The accurately known molar heat of combustion of naphthalene, $\mathrm{C}_{10} \mathrm{H}_{8}(\mathrm{~s}), \Delta H=-5156.8 \mathrm{~kJ} / \mathrm{mol} \mathrm{C}_{10} \mathrm{H}_{8}$, is
used to calibrate calorimeters. The complete combustion of $0.01520 \mathrm{~g}$ of $\mathrm{C}_{10} \mathrm{H}_{8}$ at constant pressure raises the temperature of a calorimeter by $0.212^{\circ} \mathrm{C}$. Find the heat capacity of the calorimeter. (b) The initial temperature of the calorimeter (part a) is $22.102^{\circ} \mathrm{C} ; 0.1040 \mathrm{~g}$ of $\mathrm{C}_{8} \mathrm{H}_{18}(\ell)$,
octane (molar heat of combustion $\Delta H=-5451.4 \mathrm{~kJ} / \mathrm{mol}$ $\mathrm{C}_{8} \mathrm{H}_{18}$, is completely burned in the calorimeter. Find the final temperature of the calorimeter.

Anthony Han
Anthony Han
Numerade Educator
01:24

Problem 133

When a gas expands suddenly, it may not have time to absorb a significant amount of heat: $q=0 .$ Assume that $1.00 \mathrm{~mol} \mathrm{~N}_{2}$ expands suddenly, doing $3000 . \mathrm{J}$ of work.
(a) What is $\Delta E$ for the process? (b) The heat capacity of $\mathrm{N}_{2}$ is $20.9 \mathrm{~J} / \mathrm{mol} ?{ }^{\circ} \mathrm{C}$. How much does its temperature fall during this expansion? (This is the principle of most snow-making machines, which use compressed air mixed with water vapor.)

Anthony Han
Anthony Han
Numerade Educator
01:35

Problem 134

As a rubber band is stretched, it gets warmer; when released, it gets cooler. To obtain the more nearly linear arrangement of the rubber band's polymeric material from the more random relaxed rubber band requires that there be rotation about carbon-carbon single bonds. Based on these data, give the sign of $\Delta G, \Delta H$, and $\Delta S$ for the stretching of a rubber band and for the relaxing of a stretched rubber band. What drives the spontaneous process?

Aadit Sharma
Aadit Sharma
Numerade Educator
06:00

Problem 135

(a) The decomposition of mercury(II) oxide has been used as a method for producing oxygen, but this is not a recommended method. Why? (b) Write the balanced equation for the decomposition of mercury(II) oxide.
(c) Calculate the $\Delta H^{0}, \Delta S^{0}$, and $\Delta G^{0}$ for the reaction.
(d) Is the reaction spontaneous at room temperature?

Caroline Basil
Caroline Basil
Numerade Educator
06:49

Problem 136

(a) A student heated a sample of a metal weighing $32.6 \mathrm{~g}$ to $99.83^{\circ} \mathrm{C}$ and put it into $100.0 \mathrm{~g}$ of water at $23.62^{\circ} \mathrm{C}$ in a calorimeter. The final temperature was $24.41^{\circ} \mathrm{C}$. The student calculated the specific heat of the metal, but neglected to use the heat capacity of the calorimeter. The specific heat of water is $4.184 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$. What was his answer? The metal was known to be chromium, molybdenum, or tungsten. By comparing the value of the specific heat to those of the metals $\left(\mathrm{Cr}, 0.460 ; \mathrm{Mo}, 0.250 ; \mathrm{W}, 0.135 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}\right)$, the student
identified the metal. What was the metal? (b) A student at the next laboratory bench did the same experiment, obtained the same data, and used the heat capacity of the calorimeter in his calculations. The heat capacity of the calorimeter was $410 . \mathrm{J} /{ }^{\circ} \mathrm{C}$. Was his identification of the metal different?

Anthony Han
Anthony Han
Numerade Educator
01:24

Problem 137

According to the Second Law of Thermodynamics what would be the ultimate state or condition of the universe?

Aadit Sharma
Aadit Sharma
Numerade Educator
02:10

Problem 138

For each of the following changes, estimate the signs (positive, negative, or 0 ) of $\Delta S$ and $\Delta G$.
(a) The growth of a crystal from a supersaturated solution
(b) Sugar cube $+$ cup of hot tea $\longrightarrow$ cup of hot, sweetened tea
(c) $\mathrm{H}_{2} \mathrm{O}(\mathrm{s}) \longrightarrow \mathrm{H}_{2} \mathrm{O}(\ell)$

Aadit Sharma
Aadit Sharma
Numerade Educator
03:03

Problem 139

Estimate the boiling point of tin(IV) chloride, $\mathrm{Sn} \mathrm{Cl}_{4}$, at one atmosphere pressure:
$$\begin{array}{r}\mathrm{SnCl}_{4}(\ell) \leftrightharpoons \mathrm{SnCl}_{4}(\mathrm{~g}) \\
\mathrm{SnCl}_{4}(\ell): \Delta H_{\mathrm{f}}^{0}=-511.3 \mathrm{~kJ} / \mathrm{mol}, S^{0}=258.6 \mathrm{~J} / \mathrm{mol} \cdot \mathrm{K} \\
\mathrm{SnCl}_{4}(\mathrm{~g}): \Delta H_{\mathrm{f}}^{0}=-471.5 \mathrm{~kJ} / \mathrm{mol}, S^{0}=366 \mathrm{~J} / \mathrm{mol} \cdot \mathrm{K}\end{array}$$

Anthony Han
Anthony Han
Numerade Educator
03:34

Problem 140

Energy to power muscular work is produced from stored carbohydrates (glycogen) or fat (triglycerides). Metabolic consumption and production of energy are described with the nutritional "Calorie," which is equal to 1 kilocalorie. Average energy output per minute for various activities follows: sitting, $1.7$ kcal; walking, level, $3.5 \mathrm{mph}$, $5.5$ kcal; cycling, level, $13 \mathrm{mph}, 10 .$ kcal; swimming, $8.4$ kcal; running, 10. mph, 19 kcal. Approximate energy values of some common foods are also given: large apple, $100 . \mathrm{kcal}$; 8-oz cola drink, 105 kcal; malted milkshake, $500 .$ kcal; $\frac{3}{4}$ cup pasta with tomato sauce and cheese, $195 \mathrm{kcal}$; hamburger on bun with sauce, $350 . \mathrm{kcal} ; 10 .-\mathrm{oz}$ sirloin steak, including fat, $1000 .$ kcal. To maintain body weight, fuel intake should balance energy output. Prepare a table showing (a) each given food, (b) its fuel value, and (c) the minutes of each activity that would balance the kcal of each food.

Surjit Tewari
Surjit Tewari
Numerade Educator
01:16

Problem 141

From its heat of fusion, calculate the entropy change associated with the melting of one mole of ice at its melting point. From its heat of vaporization, calculate the entropy change associated with the boiling of one mole of water at its boiling point. Are your calculated values consistent with the simple model that we use to describe order in solids, liquids, and gases?

Narayan Hari
Narayan Hari
Numerade Educator
02:14

Problem 142

The energy content of dietary fat is $39 \mathrm{~kJ} / \mathrm{g}$, and for protein and carbohydrates it is 17 and $16 \mathrm{~kJ} / \mathrm{g}$, respectively. A $70.0-\mathrm{kg}(155-\mathrm{lb})$ person utilizes $335 \mathrm{~kJ} / \mathrm{h}$ while resting and $1250 . \mathrm{kJ} / \mathrm{h}$ while walking $6 \mathrm{~km} / \mathrm{h}$. How many hours would the person need to walk per day instead of resting if he or she consumed $100 . \mathrm{g}$ (about $\frac{1}{4} \mathrm{lb}$ ) of fat instead of
100. $\mathrm{g}$ of protein in order to not gain weight?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:06

Problem 143

The enthalpy change for melting one mole of water at $273 \mathrm{~K}$ is $\Delta H_{273}^{0}=6010 . \mathrm{J} / \mathrm{mol}$, whereas that for vaporizing a mole of water at $373 \mathrm{~K}$ is $\Delta H_{273}^{0}=40,660 \mathrm{~J} / \mathrm{mol}$. Why is the second value so much larger?

Aadit Sharma
Aadit Sharma
Numerade Educator
02:36

Problem 144

A $43.6-\mathrm{g}$ chunk of lead was removed from a beaker of boiling water, quickly dried, and dropped into a polystyrene cup containing $50.0 \mathrm{~g}$ of water at $25.0^{\circ} \mathrm{C}$. As the system reached equilibrium, the water temperature rose to $26.8^{\circ} \mathrm{C}$. The heat capacity of the polystyrene cup had previously been determined to be $18.6 \mathrm{~J} /{ }^{\circ} \mathrm{C}$. Calculate the molar heat capacity and the specific heat of lead.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:08

Problem 145

Methane, $\mathrm{CH}_{4}(\mathrm{~g})$, is the main constituent of natural gas. In excess oxygen, methane burns to form $\mathrm{CO}_{2}(\mathrm{~g})$ and $\mathrm{H}_{2} \mathrm{O}(\ell)$, whereas in limited oxygen, the products are $\mathrm{CO}(\mathrm{g})$ and $\mathrm{H}_{2} \mathrm{O}(\ell) .$ Which would result in a higher temperature: a gas-air flame or a gas-oxygen flame? How can you tell?

Aadit Sharma
Aadit Sharma
Numerade Educator
02:49

Problem 146

A $0.483-\mathrm{g}$ sample of butter was burned in a bomb calorimeter whose heat capacity was $4572 \mathrm{~J} /{ }^{\circ} \mathrm{C}$, and the temperature was observed to rise from $24.76$ to $27.93^{\circ} \mathrm{C}$. Calculate the fuel value of butter in (a) $\mathrm{kJ} / \mathrm{g} ;$ (b) nutritional Calories/g (one nutritional Calorie is equal to one kilocalorie); (c) nutritional Calories/5-gram pat.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:04

Problem 147

Hess's Law is also known as the Law of _____ ________ _______.

Aadit Sharma
Aadit Sharma
Numerade Educator
02:49

Problem 148

Before he became a professor of chemistry at 28 years of age, what career did Germain Hess pursue?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:15

Problem 149

Go to www-groups.dcs.st-andrews.ac.uk/ history/ Mathematicians/Gibbs.html or another site that describes the events in the life of Josiah Willard Gibbs.
(a) In what way was the doctorate degree granted to Gibbs, from whom Gibbs free energy gets its name, a first? (b) At what university did he spend nearly all his academic career?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:01

Problem 150

Use the Handbook of Cbemistry and Pbysics or another suitable reference to find the heats of formation of the following hydrocarbons: methane, ethane, propane, and $n$ -butane. (a) What are the units of the values you have found? (b) Is there a trend when you compare the formula weight of each hydrocarbon with its heat of formation?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:31

Problem 151

Why does $\mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{~s})$ have a lower entropy than $\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{~s}) ?$ There are two primary qualitative reasons for this. You may have to use the chemistry library or some other source to get more information on the properties of these two common compounds to answer the question.

Mahendra K
Mahendra K
Numerade Educator
01:13

Problem 152

Steel is made by the high-temperature reaction of iron oxide $\left(\mathrm{Fe}_{2} \mathrm{O}_{3}\right)$ with coke (a form of carbon) to produce metallic iron and $\mathrm{CO}_{2} .$ This same reaction can NOT be done with alumina $\left(\mathrm{Al}_{2} \mathrm{O}_{3}\right)$ and carbon to make metallic $\mathrm{Al}$ and $\mathrm{CO}_{2} .$ Why not? Explain fully and give thermodynamic reasons for your answer. You may need to obtain further information from outside sources on the properties of the substances involved.

Lottie Adams
Lottie Adams
Numerade Educator