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Advanced Problems in Physical Chemistry for Competitive Examinations

Neeraj Kumar

Chapter 5

Thermochemistry - all with Video Answers

Educators

Section 1

Exercises I

01:56

Problem 1

The word standard in molar enthalpy change implies
(a) temperature $298 \mathrm{~K}$ and pressure 1 atm
(b) any temperature and pressure 1 atm
(c) any temperature and pressure 1 bar
(d) any temperature and pressure

Rolly Sharda
Rolly Sharda
Numerade Educator
02:09

Problem 2

The enthalpy change in a reaction does not depend upon
(a) the state of reactants and products
(b) the nature of the reactants and products
(c) different intermediate steps in the reaction
(d) initial and final enthalpy of the system

Rolly Sharda
Rolly Sharda
Numerade Educator
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Problem 3

A quantity of $1.6 \mathrm{~g}$ sample of $\mathrm{NH}_{4} \mathrm{NO}_{3}$ is decomposed in a bomb calorimeter. The temperature of the calorimeter decreases by $6.0 \mathrm{~K}$. The heat capacity of the calorimeter system is $1.25 \mathrm{~kJ} / \mathrm{K}$. The molar heat of decomposition for $\mathrm{NH}_{4} \mathrm{NO}_{3}$ is
(a) $7.5 \mathrm{~kJ} / \mathrm{mol}$
(b) $-600 \mathrm{~kJ} / \mathrm{mol}$
(c) $-375 \mathrm{~kJ} / \mathrm{mol}$
(d) $375 \mathrm{~kJ} / \mathrm{mol}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:00

Problem 4

The difference between enthalpies of reaction at constant pressure and constant volume for the reaction:
$$2 \mathrm{C}_{6} \mathrm{H}_{6}(\mathrm{l})+15 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 12 \mathrm{CO}_{2}(\mathrm{~g})+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{I})$$
at $298 \mathrm{~K}$ in $\mathrm{kJ}$ is
(a) $-7.43$
(b) $+3.72$
(c) $-3.72$
(d) $+7.43$

Rolly Sharda
Rolly Sharda
Numerade Educator
01:39

Problem 5

Among the following the reaction for which $\Delta H=\Delta E$, is
(a) $\mathrm{PCl}_{5}(\mathrm{~g}) \rightarrow \mathrm{PCl}_{3}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g})$
(b) $\mathrm{H}_{2}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{HCl}(\mathrm{g})$
(c) $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\mathrm{l})+3 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{CO}_{2}(\mathrm{~g})$
$+3 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$
(d) $\mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{C}_{2} \mathrm{H}_{6}(\mathrm{~g})$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:17

Problem 6

The heat capacity of bomb calorimeter is $500 \mathrm{~J} /{ }^{\circ} \mathrm{C}$. A $2{ }^{\circ} \mathrm{C}$ rise in temperature has
been observed on the combustion of $0.1 \mathrm{~g}$ of methane. What is the value of $\Delta E$ per mole of methane?
(a) $1 \mathrm{~kJ}$
(b) $160 \mathrm{~kJ}$
(c) $-160 \mathrm{~kJ}$
(d) $-1 \mathrm{~kJ}$

Rolly Sharda
Rolly Sharda
Numerade Educator
01:32

Problem 7

For the reaction $\mathrm{C}(\mathrm{s})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}(\mathrm{g})$
(a) $\Delta H>\Delta E$
(b) $\Delta H<\Delta E$
(c) $\Delta H=\Delta E$
(d) $|\Delta H|>|\Delta E|$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:47

Problem 8

The enthalpy of formation of methane(g) at constant pressure is $-18,500 \mathrm{cal} / \mathrm{mol}$ at $27^{\circ} \mathrm{C}$. The enthalpy of formation at constant volume would be
(a) $-19,700 \mathrm{cal}$
(b) $-17,300$ cal
(c) $-18,498.8$ cal
(d) $-18,500 \mathrm{cal}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:34

Problem 9

When $0.18 \mathrm{~g}$ of glucose was burnt in a bomb calorimeter, the temperature rose by $4 \mathrm{~K}$. The heat capacity of the calorimeter system is $\left(\Delta_{\mathrm{C}} H^{\circ}=-2.8\right.$ $\times 10^{6} \mathrm{~J} /$ mol glucose $)$
(a) $700 \mathrm{~J} / \mathrm{K}$
(b) $700 \mathrm{~kJ} / \mathrm{K}$
(c) $126 \mathrm{~J} / \mathrm{K}$
(d) $7.0 \mathrm{~kJ} / \mathrm{K}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:46

Problem 10

Geological conditions are sometimes so extreme that quantities neglected in normal laboratory experiments take on an overriding importance. For example, consider the formation of diamond under geophysically typical conditions. The density of graphite is $2.4 \mathrm{~g} / \mathrm{cm}^{3}$ and that of diamond is $3.6 \mathrm{~g} / \mathrm{cm}^{3}$ at a certain temperature and 500 kbar. By how much does $\Delta U_{\text {trans }}$ differs from $\Delta H_{\text {trans }}$ for the graphite to diamond transition?
(a) $83.33 \mathrm{~kJ} / \mathrm{mol}$
(b) $0.83 \mathrm{~kJ} / \mathrm{mol}$
(c) $8.33 \times 10^{7} \mathrm{~kJ} / \mathrm{mol}$
(d) $83.33 \mathrm{~J} / \mathrm{mol}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:47

Problem 11

Study the following thermochemical equations:
$$\mathrm{A} \rightarrow \mathrm{B} ; \Delta H=+100 \mathrm{kcal}$$
$$\mathrm{B} \rightarrow \mathrm{C} ; \Delta H=-80 \mathrm{kcal}$$
The correct order of enthalpies of formation of $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$ is
(a) $\mathrm{A}<\mathrm{B}<\mathrm{C}$
(b) $\mathrm{A}<\mathrm{C}<\mathrm{B}$
(c) $\mathrm{C}<\mathrm{A}<\mathrm{B}$
(d) $B<C<A$

Rolly Sharda
Rolly Sharda
Numerade Educator
01:35

Problem 12

The standard enthalpy of formation of a substance
(a) is always positive
(b) is always negative
(c) is zero
(d) may be positive, negative or zero

Rolly Sharda
Rolly Sharda
Numerade Educator
02:20

Problem 13

The enthalpy of formation of ammonia gas is $-46.0 \mathrm{~kJ} / \mathrm{mol}$. The enthalpy change for the reaction:
$2 \mathrm{NH}_{3}(\mathrm{~g}) \rightarrow \mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g})$ is
(a) $46.0 \mathrm{~kJ}$
(b) $92.0 \mathrm{~kJ}$
(c) $23.0 \mathrm{~kJ}$
(d) $-92.0 \mathrm{~kJ}$

Rolly Sharda
Rolly Sharda
Numerade Educator
01:51

Problem 14

The enthalpy of formation of $\mathrm{HCl}(\mathrm{g})$ from the following reaction:
$\mathrm{H}_{2}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{HCl}(\mathrm{g})+44 \mathrm{kcal}$ is
(a) $-44$ kcal $\mathrm{mol}^{-1}$
(b) $-22$ kcal mol $^{-1}$
(c) $22 \mathrm{kcal} \mathrm{mol}^{-1}$
(d) $-88$ kcal $\mathrm{mol}^{-1}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:11

Problem 15

Formation of ozone from oxygen is an endothermic process. In the upper atmosphere, ultraviolet is the source of energy that drives the reaction. Assuming that both the reactions and the products of the reaction are in standard states, the standard enthalpy of formation of ozone from the following information:
$3 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{O}_{3}(\mathrm{~g}), \Delta H^{\circ}=286 \mathrm{~kJ}$, is
(a) $+143 \mathrm{~kJ} / \mathrm{mol}$
(b) $-143 \mathrm{~kJ} / \mathrm{mol}$
(c) $+286 \mathrm{~kJ} / \mathrm{mol}$
(d) $-286 \mathrm{~kJ} / \mathrm{mol}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:43

Problem 16

The $\Delta_{f} H^{\circ}$ for $\mathrm{CO}_{2}(\mathrm{~g}), \mathrm{CO}(\mathrm{g})$ and $\mathrm{H}_{2} \mathrm{O}(\mathrm{g})$
are $-393.5,-110.5$ and $-241.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$, respectively. The standard enthalpy change (in $\mathrm{kJ}$ ) for the reaction:
$\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g})$ is
(a) $524.1$
(b) $41.2$
(c) $-262.5$
(d) $-41.2$

Rolly Sharda
Rolly Sharda
Numerade Educator
03:23

Problem 17

The value of $\Delta_{\mathrm{f}} H^{\circ}$ of $\mathrm{U}_{3} \mathrm{O}_{8}(\mathrm{~s})$ is $-853.5 \mathrm{~kJ}$
$\mathrm{mol}^{-1} . \Delta H^{\circ}$ for the reaction: $3 \mathrm{UO}_{2}(\mathrm{~s})$
$+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{U}_{3} \mathrm{O}_{8}(\mathrm{~s})$, is $-76.00 \mathrm{~kJ} .$ The
value of $\Delta_{\mathrm{f}} H^{\circ}$ of $\mathrm{UO}_{2}(\mathrm{~s})$ is
(a) $-259.17 \mathrm{~kJ}$
(b) $-310.17 \mathrm{~kJ}$
(c) $+259.17 \mathrm{~kJ}$
(d) $930.51 \mathrm{~kJ}$.

Rolly Sharda
Rolly Sharda
Numerade Educator
02:08

Problem 18

Given enthalpy of formation of $\mathrm{CO}_{2}(\mathrm{~g})$ and $\mathrm{CaO}(\mathrm{s})$ are $-94.0 \mathrm{~kJ}$ and $-152 \mathrm{~kJ}$, respectively, and the enthalpy of the reaction: $\mathrm{CaCO}_{3}(\mathrm{~s}) \rightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g})$ is $42 \mathrm{~kJ}$. The enthalpy of formation of $\mathrm{CaCO}_{3}(\mathrm{~s})$ is
(a) $-42 \mathrm{~kJ}$
(b) $-202 \mathrm{~kJ}$
(c) $+202 \mathrm{~kJ}$
(d) $-288 \mathrm{~kJ}$

Rolly Sharda
Rolly Sharda
Numerade Educator
03:49

Problem 19

The standard enthalpies of formation of $\mathrm{NH}_{3}(\mathrm{~g}), \mathrm{CuO}(\mathrm{s})$ and $\mathrm{H}_{2} \mathrm{O}(\mathrm{l})$ are $-46$,
$-155$ and $-285 \mathrm{~kJ} / \mathrm{mol}$, respectively. The enthalpy change when $6.80 \mathrm{~g}$ of $\mathrm{NH}_{3}$ is passed over cupric oxide is
(a) $-59.6 \mathrm{~kJ}$
(b) $+59.6 \mathrm{~kJ}$
(c) $-298 \mathrm{~kJ}$
(d) $-119.2 \mathrm{~kJ}$

Rolly Sharda
Rolly Sharda
Numerade Educator
01:16

Problem 20

The standard enthalpies of formation of $\mathrm{H}_{2} \mathrm{O}(\mathrm{l}), \mathrm{Li}^{+}(\mathrm{aq})$ and $\mathrm{OH}^{-}(\mathrm{aq})$ are $-285.8$, $-278.5$ and $-228.9 \mathrm{~kJ} / \mathrm{mol}$, respectively. The standard enthalpy change for the reaction is
$2 \mathrm{Li}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow 2 \mathrm{Li}^{+}(\mathrm{aq})+2 \mathrm{OH}^{-}(\mathrm{aq})$
$+\mathrm{H}_{2}(\mathrm{~g})$
(a) $+443.2 \mathrm{~kJ}$
(b) $-443.2 \mathrm{~kJ}$
(c) $-221.6 \mathrm{~kJ}$
(d) $+221.6 \mathrm{~kJ}$

Ajay Singhal
Ajay Singhal
Numerade Educator
02:00

Problem 21

The standard enthalpy of combustion of solid boron is numerically equal to
(a) $\frac{1}{2} \Delta_{f} H_{\mathrm{B}_{2} \mathrm{O}_{3}(\mathrm{~s})}^{\mathrm{o}}$
(b) $\Delta_{f} H_{\mathrm{B}_{2} \mathrm{O}_{3}(\mathrm{~s})}^{\mathrm{o}}$
(c) $-\Delta_{f} H_{\mathrm{B}_{2} \mathrm{O}_{3}(\mathrm{~s})}^{\mathrm{o}}$
$(\mathrm{d})-\frac{1}{2} \Delta_{f} H_{\mathrm{B}_{2} \mathrm{O}_{3}(\mathrm{~s})}^{\mathrm{o}}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:19

Problem 22

The heat evolved in the combustion of glucose, $\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O}_{6}$ is $-680 \mathrm{kcal} / \mathrm{mol}$. The mass of $\mathrm{CO}_{2}$ produced, when $170 \mathrm{kcal}$ of heat is evolved in the combustion of glucose is
(a) $45 \mathrm{~g}$
(b) $66 \mathrm{~g}$
(c) $11 \mathrm{~g}$
(d) $44 \mathrm{~g}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:26

Problem 23

Standard molar enthalpy of formation of $\mathrm{CO}_{2}$ is equal to
(a) zero
(b) the standard molar enthalpy of combustion of gaseous carbon
(c) the sum of standard molar enthalpies of formation of $\mathrm{CO}$ and $\mathrm{O}_{2}$
(d) the standard molar enthalpy of combustion of carbon (graphite)

Rolly Sharda
Rolly Sharda
Numerade Educator
03:09

Problem 24

Heat evolved in the complete combustion of $1.026 \mathrm{~kg}$ sucrose at constant pressure will be
$$\begin{array}{l}
\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{~s})+12 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 12 \mathrm{CO}_{2}(\mathrm{~g}) \\
+11 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) ; \Delta H=-5.65 \times 10^{3} \mathrm{~kJ}
\end{array}$$
(a) $1.695 \times 10^{4} \mathrm{~kJ}$
(b) $5.65 \times 10^{3} \mathrm{~kJ}$
(c) $1.883 \times 10^{3} \mathrm{~kJ}$
(d) $3.22 \times 10^{4} \mathrm{~kJ}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:32

Problem 25

Enthalpies of combustion of $\mathrm{CH}_{4}$, $\mathrm{C}_{2} \mathrm{H}_{4}$ and $\mathrm{C}_{2} \mathrm{H}_{6}$ are $-890,-1411$ and $-1560 \mathrm{~kJ} / \mathrm{mole}$, respectively. Which has the highest fuel value (heat produced per gram of the fuel)?
(a) $\mathrm{CH}_{4}$
(b) $\mathrm{C}_{2} \mathrm{H}_{6}$
(c) $\mathrm{C}_{2} \mathrm{H}_{4}$
(d) all same

Rolly Sharda
Rolly Sharda
Numerade Educator
02:47

Problem 26

The enthalpy of combustion of methane is $-890 \mathrm{~kJ}$. The volume of methane at $0{ }^{\circ} \mathrm{C}$ and 1 atm to be burnt to produce $2670 \mathrm{~kJ}$ heat is
(a) $33.61$
(b) $67.21$
(c) $7.471$
(d) $11.21$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:34

Problem 27

Enthalpies of combustion of $\mathrm{CH}_{4}, \mathrm{C}_{2} \mathrm{H}_{6}$ and $\mathrm{C}_{3} \mathrm{H}_{8}$ are $-210,-370$ and $-526$ kcal/mol, respectively. Enthalpy of combustion of hexane can be predicted as
(a) $-840 \mathrm{kcal} \mathrm{mol}^{-1}$
(b) $-684 \mathrm{kcal} \mathrm{mol}^{-1}$
(c) $-1000$ kcal mol $^{-1}$
(d) $-500$ kcal $\mathrm{mol}^{-1}$

Rolly Sharda
Rolly Sharda
Numerade Educator
01:37

Problem 28

For a specific work, on an average a person requires $5616 \mathrm{~kJ}$ of energy. How many kilograms of glucose must be consumed if all the required energy has to be derived from glucose only? $\Delta H$ for combustion of glucose is $-2808 \mathrm{~kJ} \mathrm{~mol}^{-1}$.
(a) $0.720 \mathrm{~kg}$
(b) $0.36 \mathrm{~kg}$
(c) $0.18 \mathrm{~kg}$
(d) $1.0 \mathrm{~kg}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:53

Problem 29

Benzene burns in oxygen according to the following reactions:
$\mathrm{C}_{6} \mathrm{H}_{6}(\mathrm{l})+\frac{15}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 3 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})+6 \mathrm{CO}_{2}(\mathrm{~g})$
If the standard enthalpies of formation of $\mathrm{C}_{6} \mathrm{H}_{6}(\mathrm{l}), \mathrm{H}_{2} \mathrm{O}(\mathrm{l})$ and $\mathrm{CO}_{2}(\mathrm{~g})$ are $11.7$
$-68.1$ and $-94$ kcal/mole, respectively,
the amount of heat that will liberate by burning $780 \mathrm{~g}$ of benzene is
(a) $7800 \mathrm{kcal}$
(b) $780 \mathrm{kcal}$
(c) $78 \mathrm{kcal}$
(d) $608.4 \mathrm{kcal}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:15

Problem 30

The enthalpy of combustion at $25^{\circ} \mathrm{C}$ of $\mathrm{H}_{2}(\mathrm{~g})$, cyclohexane(l) and cyclohexene(l) $\begin{array}{lllll}\text { are }-241, & -3920 & \text { and } & -3800 & \mathrm{~kJ} / \mathrm{mol} \text { , }\end{array}$ respectively. $\quad$ The enthalpy of hydrogenation of cyclohexene(1) is
(a) $-121 \mathrm{~kJ} / \mathrm{mol}$
(b) $+121 \mathrm{~kJ} / \mathrm{mol}$
(c) $-242 \mathrm{~kJ} / \mathrm{mol}$
(d) $+242 \mathrm{~kJ} / \mathrm{mol}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:20

Problem 31

The enthalpy change involved in the oxidation of glucose is $-2880 \mathrm{~kJ} / \mathrm{mol}$. Twenty five per cent of this energy is available for muscular work. If $100 \mathrm{~kJ}$ of muscular work is needed to walk $1 \mathrm{~km}$, what is the maximum distance that a person will be able to walk after eating $120 \mathrm{~g}$ of glucose?
(a) $19.2 \mathrm{~km}$
(b) $9.6 \mathrm{~km}$
(c) $2.4 \mathrm{~km}$
(d) $4.8 \mathrm{~km}$

Rolly Sharda
Rolly Sharda
Numerade Educator
02:31

Problem 32

A geyser, operating on LPG (liquefied petroleum gas) heats water flowing at the rate of $3.0$ litres per minutes, from $27^{\circ} \mathrm{C}$ to $77^{\circ} \mathrm{C}$. If the heat of combustion of LPG is $40,000 \mathrm{~J} / \mathrm{g}$, how much fuel, in $\mathrm{g}$, is consumed per minute? (Specific heat capacity of water is $4200 \mathrm{~J} / \mathrm{kg}-\mathrm{K}$ )
(a) $15.25$
(b) $15.50$
(c) $15.75$
(d) $16.00$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:15

Problem 33

For the allotropic change represented by the equation: $\mathrm{C}($ graphite $) \rightarrow \mathrm{C}($ diamond $)$; $\Delta H=+1.9 \mathrm{~kJ}$. If $6.0 \mathrm{~g}$ of diamond and $6.0 \mathrm{~g}$ of graphite is burnt completely in separate experiments, then the heat liberated will be higher by
(a) $1.9 \mathrm{~kJ}$ in case of graphite
(b) $1.9 \mathrm{~kJ}$ in case of diamond
(c) $0.95 \mathrm{~kJ}$ in case of diamond
(d) $0.95 \mathrm{~kJ}$ in case of graphite

Ajay Singhal
Ajay Singhal
Numerade Educator
01:36

Problem 34

Equal volumes of one molar hydrochloric acid and one molar sulphuric acid are neutralized completely by dilute $\mathrm{NaOH}$ solution by which $X$ and $Y$ kcal of heat are liberated, respectively. Which of the following is true?
(a) $X=Y$
(b) $2 X=Y$
(c) $X=2 Y$
(d) none of these

Hunza Gilgit
Hunza Gilgit
Numerade Educator
01:22

Problem 35

Enthalpy of neutralization of oxalic acid is $-25.4 \mathrm{kcal} / \mathrm{mol}$ using strong base, $\mathrm{NaOH}$. Enthalpy change for the process:
$\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(\mathrm{aq}) \rightarrow 2 \mathrm{H}^{+}(\mathrm{aq})+\mathrm{C}_{2} \mathrm{O}_{4}^{2-}(\mathrm{aq})$ is
about
(a) $2.0 \mathrm{kcal}$
(b) $-11.7 \mathrm{kcal}$
(c) $1.0 \mathrm{kcal}$
(d) $4.0 \mathrm{kcal}$

Ajay Singhal
Ajay Singhal
Numerade Educator
00:43

Problem 36

A solution of $500 \mathrm{ml}$ of $2 \mathrm{M}-\mathrm{KOH}$ is added to $500 \mathrm{ml}$ of $2 \mathrm{M}-\mathrm{HCl}$ and the mixture is well shaken. The rise in temperature $T_{1}$ is noted. The experiment is again performed using $250 \mathrm{ml}$ of $\mathrm{KOH}$ solution and $500 \mathrm{ml}$ of $\mathrm{HCl}$ solution and rise in temperature $T_{2}$ is again noted. Which of the following is correct?
(a) $T_{1}=T_{2}$
(b) $T_{1}$ is 2 times as larger as $T_{2}$
(c) $T_{2}$ is twice larger as $T_{1}$
(d) $T_{1}$ is $1.5$ times as larger as $T_{2}$

Mishal Gul
Mishal Gul
Numerade Educator
01:34

Problem 37

Under identical conditions, how many millilitres of $1 \mathrm{M}-\mathrm{KOH}$ and $2 \mathrm{M}-\mathrm{H}_{2} \mathrm{SO}_{4}$ solutions are required to produce a resulting volume of $100 \mathrm{ml}$ with the highest rise in temperature?
(a) 80,20
(b) 20,80
(c) 60,40
(d) 50,50

Amita Prajapat
Amita Prajapat
Numerade Educator
01:22

Problem 38

Enthalpy of neutralization of the reaction between $\mathrm{CH}_{3} \mathrm{COOH}(\mathrm{aq})$ and $\mathrm{NaOH}(\mathrm{aq})$ is $-13.2 \mathrm{kcal} / \mathrm{eq}$ and that of the reaction between $\mathrm{H}_{2} \mathrm{SO}_{4}($ aq $)$ and $\mathrm{KOH}(\mathrm{aq})$ is $-13.7$ kcalleq. The enthalpy of dissociation of $\mathrm{CH}_{3} \mathrm{COOH}(\mathrm{aq})$ is
(a) $-0.5 \mathrm{kcal} \mathrm{eq}^{-1}$
(b) $+0.5 \mathrm{kcal} \mathrm{eq}^{-1}$
(c) $-26.9 \mathrm{kcal} \mathrm{eq}^{-1}$
(d) $+13.45$ kcal $\mathrm{eq}^{-1}$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:22

Problem 39

Enthalpy of neutralization of $\mathrm{H}_{3} \mathrm{PO}_{3}$ by $\mathrm{NaOH}$ is $-106.68 \mathrm{~kJ} / \mathrm{mol}$. If the enthalpy of neutralization of $\mathrm{HCl}$ by $\mathrm{NaOH}$ is $-55.84 \mathrm{~kJ} / \mathrm{mol}$. The $\Delta H_{\text {ionization }}$ of $\mathrm{H}_{3} \mathrm{PO}_{3}$
into its ions is
(a) $50.84 \mathrm{~kJ} / \mathrm{mol}$
(b) $5 \mathrm{~kJ} / \mathrm{mol}$
(c) $10 \mathrm{~kJ} / \mathrm{mol}$
(d) $2.5 \mathrm{~kJ} / \mathrm{mol}$

Ajay Singhal
Ajay Singhal
Numerade Educator
02:01

Problem 40

Given that: $\mathrm{C}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})$
$\Delta H^{\circ}=-X \mathrm{~kJ}$
$2 \mathrm{CO}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{CO}_{2}(\mathrm{~g}) ; \Delta H^{\circ}=-Y \mathrm{~kJ}$
The enthalpy of formation of carbon monoxide will be
(a) $(2 X-Y) / 2$
(b) $(Y-2 X) / 2$
(c) $2 X-Y$
(d) $Y-2 X$

Hunza Gilgit
Hunza Gilgit
Numerade Educator
03:21

Problem 41

The standard heat of combustion of propane is $-2220.1 \mathrm{~kJ} / \mathrm{mol}$. The standard heat of vaporization of liquid water is $44 \mathrm{~kJ} / \mathrm{mol}$. What is the $\Delta H^{\text {o }}$ of the reaction:
$\mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 3 \mathrm{CO}_{2}(\mathrm{~g})+4 \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) ?$
(a) $-2220.1 \mathrm{~kJ}$
(b) $-2044.1 \mathrm{~kJ}$
(c) $-2396.1 \mathrm{~kJ}$
(d) $-2176.1 \mathrm{~kJ}$

Shubham Kanungo
Shubham Kanungo
Numerade Educator
02:16

Problem 42

Calculate $\Delta_{\mathrm{f}} H$ for $\mathrm{ZnSO}_{4}(\mathrm{~s})$ from the following data:
$\mathrm{ZnS}(\mathrm{s}) \rightarrow \mathrm{Zn}(\mathrm{s})+\mathrm{S}$ (rhombic), $\Delta H_{1}$
$=44 \mathrm{kcal} / \mathrm{mol}$
$2 \mathrm{ZnS}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{ZnO}(\mathrm{s})+2 \mathrm{SO}_{2}(\mathrm{~g})$
$\Delta H_{2}=-221.88 \mathrm{kcal} / \mathrm{mol}$
$2 \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{SO}_{3}(\mathrm{~g}), \quad \Delta H_{3}$
$=-46.88 \mathrm{kcal} / \mathrm{mol}$
$\mathrm{ZnSO}_{4}(\mathrm{~s}) \rightarrow \mathrm{ZnO}(\mathrm{s})+\mathrm{SO}_{3}(\mathrm{~g}), \Delta H_{4}$
$=55.1 \mathrm{kcal} / \mathrm{mol}$
(a) $-233.48 \mathrm{kcal} / \mathrm{mol}$
(b) $-343.48 \mathrm{kcal} / \mathrm{mol}$
(c) $-434.84 \mathrm{kcal} / \mathrm{mol}$
(d) $-311.53 \mathrm{kcal} / \mathrm{mol}$

Tianyu Li
Tianyu Li
Numerade Educator
02:01

Problem 43

The value of $\Delta H_{\text {sol }}$ of anhydrous $\begin{array}{lllll}\text { copper (II) sulphate } & \text { is } & -66.11 & \mathrm{~kJ}\end{array}$
Dissolution of 1 mole of blue vitriol, [Copper (II) sulphate pentahydrate] is followed by absorption of $11.5 \mathrm{~kJ}$ of heat. The enthalpy of dehydration of blue vitriol is
(a) $-77.61 \mathrm{~kJ}$
(b) $+77.61 \mathrm{~kJ}$
(c) $-54.61 \mathrm{~kJ}$
(d) $+54.61 \mathrm{~kJ}$

Crystal Wang
Crystal Wang
Numerade Educator
04:56

Problem 44

The data below refers to gas phase reaction at constant pressure at $25^{\circ} \mathrm{C}$.
$\mathrm{CH}_{3}-\mathrm{CH}_{3} \rightarrow \mathrm{CH}_{3}-\mathrm{CH}_{2}+\mathrm{H} ;$
$\Delta H_{1}=+420 \mathrm{~kJ} \mathrm{~mol}^{-1}$
$\mathrm{CH}_{3}-\mathrm{CH}_{2} \rightarrow \mathrm{CH}_{2}=\mathrm{CH}_{2}+\mathrm{H} ;$
$\Delta H_{2}=+168 \mathrm{~kJ} \mathrm{~mol}^{-1}$
From these data, the enthalpy change $\Delta H$ for the reaction: $2 \mathrm{CH}_{3}-\mathrm{CH}_{2} \rightarrow \mathrm{CH}_{3}-\mathrm{CH}_{3}$
$+\mathrm{CH}_{2}=\mathrm{CH}_{2}$ is
(a) $+250 \mathrm{~kJ}$
(b) $+588 \mathrm{~kJ}$
(c) $-252 \mathrm{~kJ}$
(d) $-588 \mathrm{~kJ}$

Amany Waheeb
Amany Waheeb
Numerade Educator
02:03

Problem 45

Study the following thermochemical data:
$\mathrm{S}+\mathrm{O}_{2} \rightarrow \mathrm{SO}_{2} ; \quad \Delta H=-298.2 \mathrm{~kJ}$
$\mathrm{SO}_{2}+1 / 2 \mathrm{O}_{2} \rightarrow \mathrm{SO}_{3} ; \quad \Delta H=-98.2 \mathrm{~kJ}$
$\mathrm{SO}_{3}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{H}_{2} \mathrm{SO}_{4} ; \quad \Delta H=-130.2 \mathrm{~kJ}$
$\mathrm{H}_{2}+1 / 2 \mathrm{O}_{2} \rightarrow \mathrm{H}_{2} \mathrm{O} ; \quad \Delta H=-287.3 \mathrm{~kJ}$
The enthalpy of formation of $\mathrm{H}_{2} \mathrm{SO}_{4}$ at $298 \mathrm{~K}$ will be
(a) $-433.7 \mathrm{k} \mathrm{J}$
(b) $-650.3 \mathrm{~kJ}$
(c) $+320.5 \mathrm{~kJ}$
(d) $-813.9 \mathrm{~kJ}$

Rajesh Singh
Rajesh Singh
Numerade Educator
01:07

Problem 46

Based on the following thermochemical equations
$\mathrm{H}_{2} \mathrm{O}(\mathrm{g})+\mathrm{C}(\mathrm{s}) \rightarrow \mathrm{CO}(\mathrm{g})+\mathrm{H}_{2}(\mathrm{~g}) ; \Delta H$
$=131 \mathrm{~kJ}$
$\mathrm{CO}(\mathrm{g})+1 / 2 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g}) ; \Delta H=-282 \mathrm{~kJ}$
$\mathrm{H}_{2}(\mathrm{~g})+1 / 2 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) ; \Delta H=-242 \mathrm{~kJ}$
$\mathrm{C}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g}) ; \Delta H=X \mathrm{~kJ}$
The value of ' $\mathrm{X}$ 'will be
(a) $-393 \mathrm{~kJ}$
(b) $-655 \mathrm{~kJ}$
(c) $+393 \mathrm{~kJ}$
(d) $+655 \mathrm{~kJ}$

Mishal Gul
Mishal Gul
Numerade Educator
01:14

Problem 47

Enthalpies of solution of $\mathrm{BaCl}_{2}(\mathrm{~s})$ and $\mathrm{BaCl}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{s})$ are $-20.6 \mathrm{~kJ} / \mathrm{mol}$ and $8.8 \mathrm{~kJ} / \mathrm{mol}$, respectively. $\Delta H$ hydration of $\mathrm{BaCl}_{2}(\mathrm{~s})$ to $\mathrm{BaCl}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{s})$ is
(a) $-29.4 \mathrm{~kJ}$
(b) $-11.8 \mathrm{~kJ}$
(c) $29.6 \mathrm{~kJ}$
(d) $11.8 \mathrm{~kJ}$

Mahipal Kumawat
Mahipal Kumawat
Numerade Educator
02:21

Problem 48

The dissolution of $\mathrm{CaCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}$ in a large volume of water is endothermic to the extent of $3.5 \mathrm{kcal} / \mathrm{mol}$. For the reaction, $\mathrm{CaCl}_{2}(\mathrm{~s})+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{CaCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}(\mathrm{s})$ $\Delta H$ is $-23.2$ kcal. The heat of solution of anhydrous $\mathrm{CaCl}_{2}$ in large quantity of water will be
(a) $-26.7 \mathrm{kcal} \mathrm{mol}^{-1}$
(b) $-19.7$ kcal $\mathrm{mol}^{-1}$
(c) $19.7 \mathrm{kcal} \mathrm{mol}^{-}$
(d) $26.7 \mathrm{kcal} \mathrm{mol}^{-1}$

Aashna Calidas
Aashna Calidas
Numerade Educator
02:22

Problem 49

Given two processes:
(i) $1 / 2 \mathrm{P}_{4}(\mathrm{~s})+3 \mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{PCl}_{3}(1) ; \Delta H$
$=-635 \mathrm{~kJ}$
(ii) $\mathrm{PCl}_{3}(\mathrm{l})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow \mathrm{PCl}_{5}(\mathrm{~s}) ; \Delta H$
$=-137 \mathrm{~kJ}$
The value of $\Delta_{\mathrm{f}} H$ of $\mathrm{PCl}_{5}(\mathrm{~s})$ is
(a) $454.5 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(b) $-454.5 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(c) $-772 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(d) $-498 \mathrm{~kJ} \mathrm{~mol}^{-1}$

Lottie Adams
Lottie Adams
Numerade Educator
01:41

Problem 50

Calculate $\Delta_{\mathrm{f}} H^{\circ}$ for aqueous chloride ion from the following data:
$\frac{1}{2} \mathrm{H}_{2}(\mathrm{~g})+\frac{1}{2} \mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow \mathrm{HCl}(\mathrm{g}), \quad \Delta_{\mathrm{f}} H^{\mathrm{o}}$
$=-92.4 \mathrm{~kJ}$
$\mathrm{HCl}(\mathrm{g})+n \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{H}^{+}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq})$
$\Delta H^{\circ}=-74.8 \mathrm{~kJ}$
$\Delta_{\mathrm{f}} H^{\circ}\left(\mathrm{H}^{+}\right.$, aq. $)=0.0 \mathrm{~kJ}$
(a) $0.0$
(b) $+83.6 \mathrm{~kJ}$
(c) $+167.2 \mathrm{~kJ}$
(d) $-167.2 \mathrm{~kJ}$

Hunza Gilgit
Hunza Gilgit
Numerade Educator
01:24

Problem 51

Tungsten carbide is very hard and is used to make cutting tools and rock drills. What is the enthalpy of formation (in $\mathrm{kJ} / \mathrm{mol}$ ) of tungsten carbide? The enthalpy change for this reaction is difficult of measure directly, because the reaction occurs at $1400^{\circ} \mathrm{C}$. However, the enthalpies of combustion of the elements and of tungsten carbide can be measured easily.
$2 \mathrm{~W}(\mathrm{~s})+3 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{WO}_{3}(\mathrm{~s}) ; \Delta H$
$=-1680.6 \mathrm{~kJ}$
$\mathrm{C}($ graphite $)+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g}) ; \quad \Delta H$
$=-393.5 \mathrm{~kJ}$
$2 \mathrm{WC}(\mathrm{s})+5 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{WO}_{3}(\mathrm{~s})+2 \mathrm{CO}_{2}(\mathrm{~g})$
$\Delta H=-2391.6 \mathrm{~kJ}$
(a) $-38.0$
(b) $-76.0$
(c) $-19.0$
(d) $-1233.8$

David Collins
David Collins
Numerade Educator
01:11

Problem 52

Diborane is a potential rocket fuel which undergoes combustion according to the reaction:
$\mathrm{B}_{2} \mathrm{H}_{6}(\mathrm{~g})+3 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{B}_{2} \mathrm{O}_{3}(\mathrm{~s})+3 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$
From the following data, calculate the enthalpy change for the combustion of diborane.
$2 \mathrm{~B}(\mathrm{~s})+3 / 2 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{B}_{2} \mathrm{O}_{3}(\mathrm{~s}) ; \Delta H$
$=-1273 \mathrm{~kJ} / \mathrm{mol}$
$\mathrm{H}_{2}(\mathrm{~g})+1 / 2 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) ; \Delta H=-286$
$\mathrm{kJ} / \mathrm{mol}$
$\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) ; \Delta H=44 \mathrm{~kJ} / \mathrm{mol}$
$2 \mathrm{~B}(\mathrm{~s})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{B}_{2} \mathrm{H}_{6}(\mathrm{~g}) ; \Delta H=36 \mathrm{~kJ} / \mathrm{mol}$
(a) $-2167 \mathrm{~kJ} / \mathrm{mol}$
(b) $-1478 \mathrm{~kJ} / \mathrm{mol}$
(c) $-2035 \mathrm{~kJ} / \mathrm{mol}$
(d) $-1999 \mathrm{~kJ} / \mathrm{mol}$

David Collins
David Collins
Numerade Educator
01:51

Problem 53

Calculate the enthalpy of formation (in $\mathrm{kcal} / \mathrm{mol}$ ) of anhydrous $\mathrm{Al}_{2} \mathrm{Cl}_{6}$ from the
following data:
$2 \mathrm{Al}(\mathrm{s})+6 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{Al}_{2} \mathrm{Cl}_{6}(\mathrm{aq})+3 \mathrm{H}_{2}(\mathrm{~g})$
$\Delta H=-239.760 \mathrm{kcal}$
$\mathrm{H}_{2}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{HCl}(\mathrm{g}) ; \Delta H=-44 \mathrm{kcal}$
$\mathrm{HCl}(\mathrm{g})+\mathrm{aq} \rightarrow \mathrm{HCl}(\mathrm{aq}) ; \quad \Delta H$
$=-17.315 \mathrm{kcal}$
$\mathrm{Al}_{2} \mathrm{Cl}_{6}(\mathrm{~s})+\mathrm{aq} \rightarrow \mathrm{Al}_{2} \mathrm{Cl}_{6}(\mathrm{aq}) ; \Delta H$
$=-153.690 \mathrm{kcal}$
(a) $-371.76$
(b) $-321.960$
(c) $-218.07$
(d) $-525.45$

Rolly Sharda
Rolly Sharda
Numerade Educator
01:28

Problem 54

Which of the following salts shall cause more cooling when one mole of the salt is dissolved in the same amount of water? (Integral heat of solution at $298 \mathrm{~K}$ is given for each solute.)
(a) $\mathrm{KNO}_{3} ; \Delta H=35.4 \mathrm{~kJ} / \mathrm{mol}$
(b) $\mathrm{NaCl} ; \Delta H=5.35 \mathrm{~kJ} / \mathrm{mol}$
(c) $\mathrm{KOH} ; \Delta H=-55.6 \mathrm{~kJ} / \mathrm{mol}$
(d) $\mathrm{HBr} ; \Delta H=-83.3 \mathrm{~kJ} / \mathrm{mol}$

Amita Prajapat
Amita Prajapat
Numerade Educator
01:20

Problem 55

When 1 mole of $\mathrm{Na}(\mathrm{s})$ is dissolved in large volume of water at $298 \mathrm{~K}$ and 1 bar, $184 \mathrm{~kJ} / \mathrm{mol}$ heat is released. When $1 \mathrm{~mole}$
of $\mathrm{Na}_{2} \mathrm{O}(\mathrm{s})$ is dissolved in large volume of water at $298 \mathrm{~K}$ and 1 bar, $238 \mathrm{~kJ} / \mathrm{mol}$. If the enthalpy of formation of water is $-286 \mathrm{~kJ} / \mathrm{mol}$, then the enthalpy of formation of sodium oxide is
(a) $+54 \mathrm{~kJ} / \mathrm{mol}$
(b) $+156 \mathrm{~kJ} / \mathrm{mol}$
(c) $-416 \mathrm{~kJ} / \mathrm{mol}$
(d) $-130 \mathrm{~kJ} / \mathrm{mol}$

Shubham Kanungo
Shubham Kanungo
Numerade Educator
01:58

Problem 56

The factor of $\Delta G$ values is important in metallurgy. The $\Delta G$ values for the following reactions at $800^{\circ} \mathrm{C}$ are given as:
$\mathrm{S}_{2}(\mathrm{~s})+2 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{SO}_{2}(\mathrm{~g}) ; \Delta G=-544 \mathrm{~kJ}$
$2 \mathrm{Zn}(\mathrm{s})+\mathrm{S}_{2}(\mathrm{~s}) \rightarrow 2 \mathrm{ZnS}(\mathrm{s}) ; \Delta G=-293 \mathrm{~kJ}$
$2 \mathrm{Zn}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{ZnO}(\mathrm{s}) ; \Delta G=-480 \mathrm{~kJ}$
The $\Delta G$ for the reaction: $2 \mathrm{ZnS}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{~g})$
$\rightarrow 2 \mathrm{ZnO}(\mathrm{s})+2 \mathrm{SO}_{2}(\mathrm{~g})$ will be
(a) $-357 \mathrm{~kJ}$
(b) $-731 \mathrm{~kJ}$
(c) $-773 \mathrm{~kJ}$
(d) $-229 \mathrm{~kJ}$

Mahipal Kumawat
Mahipal Kumawat
Numerade Educator
01:04

Problem 57

Consider the reaction,
$\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(\mathrm{~g})+6 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 6 \mathrm{CO}_{2}(\mathrm{~g})+6 \mathrm{H}_{2} \mathrm{O}(1)$
Which of the following expressions is incorrect?
(a) $\Delta H^{\circ}$ reaction $=6 \Delta_{\mathrm{f}} H^{\circ}\left(\mathrm{CO}_{2}, \mathrm{~g}\right)$
$+6 \Delta_{\mathrm{f}} H^{\circ}\left(\mathrm{H}_{2} \mathrm{O}, l\right)-6 \Delta_{\mathrm{f}} H^{\circ}\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}, \mathrm{~s}\right)$
(b) $\Delta G_{\text {reaction }}^{\circ}=6 \Delta_{\mathrm{f}} G^{\circ}\left(\mathrm{CO}_{2}, \mathrm{~g}\right)+$
$6 \Delta_{\mathrm{f}} G^{\circ}\left(\mathrm{H}_{2} \mathrm{O}, l\right)-6 \Delta_{\mathrm{f}} G^{\circ}\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}, \mathrm{~s}\right)$
(c) $\Delta S_{\text {reaction }}^{\circ}=6 S^{\circ}\left(\mathrm{CO}_{2}, \mathrm{~g}\right)+6 S^{\circ}\left(\mathrm{H}_{2} \mathrm{O}, l\right)$
$-6 S^{\circ}\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}, \mathrm{~s}\right)$
(d) $\Delta S_{\text {reaction }}^{\circ}=6 S^{\circ}\left(\mathrm{CO}_{2}, \mathrm{~g}\right)+6 S^{\circ}\left(\mathrm{H}_{2} \mathrm{O}, l\right)$
$-6 S^{\circ}\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}, \mathrm{~s}\right)-S^{\circ}\left(\mathrm{O}_{2}, \mathrm{~g}\right)$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:27

Problem 58

Calculate the free energy change for the reaction: $\mathrm{H}_{2}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{HCl}(\mathrm{g})$ by
using the following data at the reaction temperature of $27^{\circ} \mathrm{C}$.
Bond enthalpies $(\mathrm{kJ} / \mathrm{mol})$ :
$\mathrm{H}-\mathrm{H}=435 ; \mathrm{Cl}-\mathrm{Cl}=240 ; \mathrm{H}-\mathrm{Cl}=430$
Entropies (J/K-mol):
$\mathrm{H}_{2}=130 ; \mathrm{Cl}_{2}=222 ; \mathrm{HCl}=186$
(a) $-185 \mathrm{~kJ}$
(b) $-20 \mathrm{~kJ}$
(c) $-179 \mathrm{~kJ}$
(d) $-191 \mathrm{~kJ}$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:34

Problem 59

The $\Delta G^{\circ}$ values for the hydrolysis of creatine phosphate (creatine-P) and glucose-6-phosphate $(\mathrm{G}-6-\mathrm{P})$ are
(i) Creatine-P $+\mathrm{H}_{2} \mathrm{O} \rightarrow$ Creatine $+\mathrm{P}$
$\Delta G^{\mathrm{o}}=-29.2 \mathrm{~kJ}$
(ii) $\mathrm{G}-6-\mathrm{P}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{G}+\mathrm{P} ; \Delta G^{\mathrm{o}}=-12.4 \mathrm{~kJ}$
$\Delta G^{0}$ for the reaction: $\mathrm{G}-6-\mathrm{P}+$ Creatine $\rightarrow \mathrm{G}+$ Creatine- $\mathrm{P}$, is
(a) $+16.8 \mathrm{~kJ}$
(b) $-16.8 \mathrm{~kJ}$
(c) $-41.6 \mathrm{~kJ}$
(d) $+41.6 \mathrm{~kJ}$

Prashant Bana
Prashant Bana
Numerade Educator
06:58

Problem 60

Calculate the standard free energy change for the ionization: $\mathrm{HF}(\mathrm{aq}) \rightarrow \mathrm{H}^{+}(\mathrm{aq})$
$+\mathrm{F}^{-}(\mathrm{aq})$ from the following data:
$\mathrm{HF}(\mathrm{aq}) \rightarrow \mathrm{HF}(\mathrm{g}) ; \Delta G^{\circ}=23.9 \mathrm{~kJ}$
$\mathrm{HF}(\mathrm{g}) \rightarrow \mathrm{H}(\mathrm{g})+\mathrm{F}(\mathrm{g}) ; \Delta G^{\circ}=555.1 \mathrm{~kJ}$
$\mathrm{H}(\mathrm{g}) \rightarrow \mathrm{H}^{+}(\mathrm{g})+\mathrm{e} ; \Delta G^{\circ}=1320.2 \mathrm{~kJ}$
$\mathrm{F}(\mathrm{g})+\mathrm{e} \rightarrow \mathrm{F}^{-}(\mathrm{g}) ; \Delta G^{\circ}=-347.5 \mathrm{~kJ}$
$\mathrm{H}^{+}(\mathrm{g})+\mathrm{F}^{-}(\mathrm{g}) \stackrel{\mathrm{aq} .}{\longrightarrow} \mathrm{H}^{+}(\mathrm{aq})+\mathrm{F}^{-}(\mathrm{aq})$
$\Delta G^{\circ}=-1513.6 \mathrm{~kJ}$
(a) $-38.1 \mathrm{~kJ}$
(b) $+38.1 \mathrm{~kJ}$
(c) $-1489.7 \mathrm{~kJ}$
(d) $-1513.6 \mathrm{~kJ}$

Iryna Ivaniuk
Iryna Ivaniuk
Numerade Educator
10:38

Problem 61

Calculate the standard free energy of the reaction at $27^{\circ} \mathrm{C}$ for the combustion of methane using the given data: $\mathrm{CH}_{4}(\mathrm{~g})$ $+2 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})$
$$\begin{array}{lcccc}
\hline \text { Species } & \mathbf{C H}_{4}(\mathrm{~g}) & \mathrm{O}_{2}(\mathrm{~g}) & \mathrm{CO}_{2}(\mathrm{~g}) & \mathbf{H}_{2} \mathrm{O}(\mathrm{l}) \\
\hline \Delta_{\mathrm{f}} \boldsymbol{H}^{\circ} /(\mathrm{kJ} & -74.5 & 0 & -393.5 & -286.0 \\
\left.\mathrm{~mol}^{-1}\right) & & & & \\
\boldsymbol{S}^{\circ} /\left(\mathrm{JK}^{-1}\right. & 186 & 205 & 212 & 70 \\
\left.\mathbf{m o l}^{-1}\right) & & & & \\
\hline
\end{array}$$
(a) $-891.0 \mathrm{~kJ} / \mathrm{mol}$
(b) $-240 \mathrm{~kJ} / \mathrm{mol}$
(c) $-819 \mathrm{~kJ} / \mathrm{mol}$
(d) $-963 \mathrm{~kJ} / \mathrm{mol}$

Pam Owens
Pam Owens
Numerade Educator
01:04

Problem 62

$\Delta_{\mathrm{f}} H^{\mathrm{o}}$ for $\mathrm{NF}_{3}(\mathrm{~g})$ is $-113 \mathrm{~kJ} / \mathrm{mol}$. Bond
energy for the $\mathrm{N}-\mathrm{F}$ bond is $273.5 \mathrm{~kJ} /$ mol. The bond energies of $\mathrm{N}_{2}$ and $\mathrm{F}_{2}$, if their magnitudes are in the ratio $6: 1$, are, respectively,
(a) $822.6,137.1 \mathrm{~kJ} / \mathrm{mol}$
(b) $979.8,163.3 \mathrm{~kJ} / \mathrm{mol}$
(c) $943.32,157.22 \mathrm{~kJ} / \mathrm{mol}$
(d) $762.6,127.1 \mathrm{~kJ} / \mathrm{mol}$

Freddie Montague
Freddie Montague
Numerade Educator
01:22

Problem 63

Among the following, for which reaction heat of reaction represents bond energy of $\mathrm{HCl}$ ?
(a) $\mathrm{HCl}(\mathrm{g}) \rightarrow \mathrm{H}(\mathrm{g})+\mathrm{Cl}(\mathrm{g})$
(b) $2 \mathrm{HCl}(\mathrm{g}) \rightarrow \mathrm{H}_{2}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g})$
(c) $\mathrm{HCl}(\mathrm{g}) \rightarrow 1 / 2 \mathrm{H}_{2}(\mathrm{~g})+1 / 2 \mathrm{Cl}_{2}(\mathrm{~g})$
(d) $\mathrm{HCl}(\mathrm{g}) \rightarrow \mathrm{H}^{+}(\mathrm{g})+\mathrm{Cl}^{-}(\mathrm{g})$

Ajay Singhal
Ajay Singhal
Numerade Educator
02:09

Problem 64

The bond energies (in $\mathrm{kJ} / \mathrm{mol}$ ) at $25^{\circ} \mathrm{C}$ are $\mathrm{C}-\mathrm{C}=346, \mathrm{C}-\mathrm{H}=413, \mathrm{H}-\mathrm{H}=437$
$\mathrm{C}=\mathrm{C} ; 611 .$ From these data, the value of $\Delta H$ at $25^{\circ} \mathrm{C}$ for the above reaction is
(a) $-289 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(b) $-124 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(c) $124 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(d) $289 \mathrm{~kJ} \mathrm{~mol}^{-1}$

Mahipal Kumawat
Mahipal Kumawat
Numerade Educator
01:27

Problem 65

Heat evolved in the reaction $\mathrm{H}_{2}(\mathrm{~g})$ $+\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{HCl}(\mathrm{g})$ is $182 \mathrm{~kJ}$. Bond energies of $\mathrm{H}-\mathrm{H}=430 \mathrm{~kJ} / \mathrm{mole}$ and $\mathrm{Cl}-\mathrm{Cl}$
$=242 \mathrm{~kJ} / \mathrm{mole}$. The $\mathrm{H}-\mathrm{Cl}$ bond energy is
(a) $763 \mathrm{~kJ} / \mathrm{mole}$
(b) $245 \mathrm{~kJ} / \mathrm{mole}$
(c) $336 \mathrm{~kJ} / \mathrm{mole}$
(d) $154 \mathrm{~kJ} / \mathrm{mole}$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:27

Problem 66

$\Delta H$ for the reaction $2 \mathrm{C}(\mathrm{s})+3 \mathrm{H}_{2}(\mathrm{~g})$ $\rightarrow \mathrm{C}_{2} \mathrm{H}_{6}(\mathrm{~g})$ is $-20.24 \mathrm{kcal} / \mathrm{mol}$. The bond energies (in kcal/mol) of $\mathrm{C}-\mathrm{C}, \mathrm{C}-\mathrm{H}$ and $\mathrm{H}-\mathrm{H}$ are $63,85.6$ and $102.6$, respectively. The enthalpy of sublimation of $\mathrm{C}(\mathrm{s})$ is
(a) $124.3 \mathrm{kcal} / \mathrm{mol}$
(b) $185.3 \mathrm{kcal} / \mathrm{mol}$
(c) $158.3 \mathrm{kcal} / \mathrm{mol}$
(d) $211.5 \mathrm{kcal} / \mathrm{mol}$

Mahipal Kumawat
Mahipal Kumawat
Numerade Educator
03:41

Problem 67

Sublimation energy of $\mathrm{Ca}$ is $121 \mathrm{~kJ} / \mathrm{mol}$. Dissociation energy of $\mathrm{Cl}_{2}$ is $242.8 \mathrm{~kJ} / \mathrm{mol}$, the total ionization energy of $\mathrm{Ca}(\mathrm{g})$ $\rightarrow \mathrm{Ca}^{2+}(\mathrm{g})$ is $2422 \mathrm{~kJ} / \mathrm{mol}$ and electron
affinity of $\mathrm{Cl}$ is $-355 \mathrm{~kJ} / \mathrm{mol}$. Lattice energy of $\mathrm{CaCl}_{2}$ is $-2430.8 \mathrm{~kJ} / \mathrm{mol}$. What is $\Delta H$ for the process $\mathrm{Ca}(\mathrm{s})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow \mathrm{CaCl}_{2}(\mathrm{~s})$ ?
(a) $-355 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(b) $+3550 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(c) $-35.5 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(d) $-1720 \mathrm{~kJ} \mathrm{~mol}^{-1}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:37

Problem 68

The following are various $\Delta H$ values $(\mathrm{kJ}$ per mol $): \Delta_{\mathrm{f}} H(\mathrm{NaCl})=-411.2 ; \Delta_{\mathrm{f}} H$
$(\mathrm{Na}, \mathrm{g})=107.3 ; \Delta_{\mathrm{f}} H(\mathrm{Cl}, \mathrm{g})=121.7 ; \Delta_{\mathrm{i}} H$
$(\mathrm{Na}, \mathrm{g})=495.4 ; \Delta_{\mathrm{eg}} H(\mathrm{Cl}, \mathrm{g})=348.5$. The
Lattice enthalpy of $\mathrm{NaCl}(\mathrm{s})$ is
(a) $495.4 \mathrm{~kJ}$
(b) $107.3 \mathrm{~kJ}$
(c) $411.2 \mathrm{~kJ}$
(d) $787.1 \mathrm{~kJ}$

Ahmed Ali
Ahmed Ali
Numerade Educator
02:04

Problem 69

Theenthalpy of hydrogenation of benzene is $-49.8 \mathrm{kcal} / \mathrm{mol}$ while its resonance energy is $36.0$ kcal/mol. The enthalpy of hydrogenation of cyclohexane is
(a) $-4.6 \mathrm{kcal}$
(b) $-28.6 \mathrm{kcal} / \mathrm{mol}$
(c) $-85.8 \mathrm{kcal} / \mathrm{mol}$
(d) $-13.8 \mathrm{kcal} / \mathrm{mol}$

Qudsiya Anis
Qudsiya Anis
Numerade Educator
02:04

Problem 70

The enthalpy of hydrogenation of benzene is $-51.0$ kcal/mol. If enthalpy of hydrogenation of 1,4 -cyclohexadiene and cyclohexene is $-58 \mathrm{kcal} / \mathrm{mol}$ and $-29 \mathrm{kcal} / \mathrm{mol}$, respectively, what is the resonance energy of benzene?
(a) $29 \mathrm{kcal} / \mathrm{mole}$
(b) $36 \mathrm{kcal} / \mathrm{mole}$
(c) $58 \mathrm{kcal} / \mathrm{mole}$
(d) $7 \mathrm{kcal} / \mathrm{mole}$

Qudsiya Anis
Qudsiya Anis
Numerade Educator
02:30

Problem 71

Use the following data to calculate the enthalpy of hydration for caesium iodide and caesium hydroxide, respectively:
$$\begin{array}{ccc}
\hline \text { Compound } & \begin{array}{c}
\text { Lattice energy } \\
\text { (kJ/mol) }
\end{array} & \begin{array}{c}
\Delta \boldsymbol{H}_{\text {Solution }} \\
\text { (kJ/mol) }
\end{array} \\
\hline \text { CsI } & +604 & +33 \\
\text { CsOH } & +724 & -72 \\
\hline
\end{array}$$
(a) $-571 \mathrm{~kJ} / \mathrm{mol}$ and $-796 \mathrm{~kJ} / \mathrm{mol}$
(b) $637 \mathrm{~kJ} / \mathrm{mol}$ and $652 \mathrm{~kJ} / \mathrm{mol}$
(c) $-637 \mathrm{~kJ} / \mathrm{mol}$ and $-652 \mathrm{~kJ} / \mathrm{mol}$
(d) $571 \mathrm{~kJ} / \mathrm{mol}$ and $796 \mathrm{~kJ} / \mathrm{mol}$

Lottie Adams
Lottie Adams
Numerade Educator
05:39

Problem 72

From the following thermochemical equations, find out bond dissociation enthalpy of $\mathrm{CH}_{3}-\mathrm{H}$ bond.
$\mathrm{CH}_{3} \mathrm{I}(\mathrm{g}) \rightarrow \mathrm{CH}_{3}(\mathrm{~g})+\mathrm{I}(\mathrm{g}) ; \Delta H=54.0 \mathrm{kcal}$
$\mathrm{CH}_{4}(\mathrm{~g})+\mathrm{I}_{2}(\mathrm{~s}) \rightarrow \mathrm{CH}_{3} \mathrm{I}(\mathrm{g})+\mathrm{HI}(\mathrm{g}) ; \Delta H$
$=29.0 \mathrm{kcal}$ $\mathrm{HI}(\mathrm{g}) \rightarrow \mathrm{H}(\mathrm{g})+\mathrm{I}(\mathrm{g}) ; \Delta H=79.8 \mathrm{kcal}$
$\mathrm{I}_{2}(\mathrm{~s}) \rightarrow 2 \mathrm{I}(\mathrm{g}) ; \Delta H=51.0 \mathrm{kcal}$
(a) $125.2 \mathrm{kcal} / \mathrm{mol}$
(b) $91.7 \mathrm{kcal} / \mathrm{mol}$
(c) $101.9 \mathrm{kcal} / \mathrm{mol}$
(d) $111.8 \mathrm{kcal} / \mathrm{mol}$

Madeline Currie
Madeline Currie
Numerade Educator
01:55

Problem 73

Estimate the average $\mathrm{S}-\mathrm{F}$ bond energy in $\mathrm{SF}_{6} .$ The values of standard enthalpy of formation of $\mathrm{SF}_{6}(\mathrm{~g}), \mathrm{S}(\mathrm{g})$ and $\mathrm{F}(\mathrm{g})$ are
$-1100,275$ and $80 \mathrm{~kJ} / \mathrm{mol}$, respectively.
(a) $183.33 \mathrm{~kJ} / \mathrm{mol}$
(b) $309.17 \mathrm{~kJ} / \mathrm{mol}$
(c) $366.37 \mathrm{~kJ} / \mathrm{mol}$
(d) $345 \mathrm{~kJ} / \mathrm{mol}$

David Collins
David Collins
Numerade Educator
01:20

Problem 74

The enthalpy of atomization of $\mathrm{PH}_{3}(\mathrm{~g})$ is $+954 \mathrm{~kJ} / \mathrm{mol}$ and that of $\mathrm{P}_{2} \mathrm{H}_{4}$ is $+1.488$
MJ/mol. The bond energy of the P-P bond is
(a) $318 \mathrm{~kJ} / \mathrm{mol}$
(b) $372 \mathrm{~kJ} / \mathrm{mol}$
(c) $213 \mathrm{~kJ} / \mathrm{mol}$
(d) $534 \mathrm{~kJ} / \mathrm{mol}$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:42

Problem 75

The standard molar enthalpies of formation of cyclohexane (1) and benzene(1) at $298 \mathrm{~K}$ are $-156$ and $+49 \mathrm{~kJ} / \mathrm{mol}$, respectively. The standard enthalpy of $\quad$ hydrogenation of cyclohexene (1) at $298 \mathrm{~K}$ is $-119 \mathrm{~kJ} / \mathrm{mol}$. Use these data to estimate the magnitude of the resonance energy of benzene.
(a) $152 \mathrm{~kJ} / \mathrm{mol}$
(b) $250 \mathrm{~kJ} / \mathrm{mol}$
(c) $12 \mathrm{~kJ} / \mathrm{mol}$
(d) $86 \mathrm{~kJ} / \mathrm{mol}$

Hunza Gilgit
Hunza Gilgit
Numerade Educator
02:26

Problem 76

Calculate the magnitude of resonance energy of $\mathrm{CO}_{2}$ from the following data (in $\mathrm{kJ} / \mathrm{mol}$ ):
Bond energies: $\mathrm{C}=\mathrm{O}=539.0, \mathrm{O}=\mathrm{O}=498.0$
Heat of sublimation of $\mathrm{C}(\mathrm{s})=718.0$
Heat of combustion of $\mathrm{C}(\mathrm{s})=-393.0$
(a) 255
(b) 531
(c) 138
(d) 247

Mahipal Kumawat
Mahipal Kumawat
Numerade Educator
01:42

Problem 77

$\mathrm{AB}, \mathrm{A}_{2}$ and $\mathrm{B}_{2}$ are diatomic molecules. If the bond enthalpies of $\mathrm{A}_{2}, \mathrm{AB}$ and $\mathrm{B}_{2}$ are in the ratio $2: 2: 1$ and enthalpy of formation $\mathrm{AB}$ from $\mathrm{A}_{2}$ and $\mathrm{B}_{2}$ is $-100 \mathrm{~kJ}$ $\mathrm{mole}^{-1} .$ What is the bond energy of $\mathrm{A}_{2}$ ?
(a) $200 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(b) $100 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(c) $300 \mathrm{~kJ} \mathrm{~mol}^{-}$
(d) $400 \mathrm{~kJ} \mathrm{~mol}^{-1}$

Hunza Gilgit
Hunza Gilgit
Numerade Educator
01:30

Problem 78

The lattice energy of solid $\mathrm{NaCl}$ is 180 kcal/mol. The dissolution of the solid in water, in the form of ions is endothermic to the extent of $1 \mathrm{kcal} / \mathrm{mol}$. If the solvation energies of $\mathrm{Na}^{+}$ and $\mathrm{Cl}^{-}$ ions are in the ratio $6: 5$, what is the enthalpy of hydration of sodium ion?
(a) $-85.6 \mathrm{kcal} / \mathrm{mol}$
(b) $-97.6 \mathrm{kcal} / \mathrm{mol}$
(c) $82.6 \mathrm{kcal} / \mathrm{mol}$
(d) $100 \mathrm{kcal} / \mathrm{mol}$

Hunza Gilgit
Hunza Gilgit
Numerade Educator
01:15

Problem 79

The enthalpy of atomization of graphite is $698.6 \mathrm{~kJ} / \mathrm{mol}$ and the mean bond enthalpy of $\mathrm{C}-\mathrm{C}$ bond in diamond is $348.4 \mathrm{~kJ} / \mathrm{mol}$. The enthalpy of conversion of graphite into diamond is
(a) $+1.2 \mathrm{~kJ} / \mathrm{mol}$
(b) $+1.8 \mathrm{~kJ} / \mathrm{mol}$
(c) $-1.2 \mathrm{~kJ} / \mathrm{mol}$
(d) $-1.8 \mathrm{~kJ} / \mathrm{mol}$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:30

Problem 80

The lattice energy of $\mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{~s})$ is $205 \mathrm{~kJ} / \mathrm{mol}$ and the hydration energies of $\mathrm{Na}^{+}$ and $\mathrm{CO}_{3}^{2-}$ ions are $-80$ and $-40 \mathrm{~kJ} / \mathrm{mol}$, respectively. The correct prediction about the solubility of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ in water is (Assume that $\Delta H$ is independent of temperature.)
(a) increases with increase in temperature
(b) decreases with increase in temperature
(c) unaffected by the change in temperature
(d) first increases and then decreases with the increase in temperature

Hunza Gilgit
Hunza Gilgit
Numerade Educator