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Heat and Thermodynamics

M. W. Zemansky, Richard H. Dittman

Chapter 16

Ideal-Gas Reactions - all with Video Answers

Educators


Chapter Questions

01:11

Problem 1

Show that the law of mass action may be written
$$
\frac{p_{3}^{n} p_{4}^{\eta_{4}}}{p_{1}^{n_{1}} p_{2}^{n_{2}}}=K
$$
where the $p$ 's are the equilibrium values of the partial pressures.

Adriano Chikande
Adriano Chikande
Numerade Educator
04:26

Problem 2

If we start with $n_{0}$ moles of $\mathrm{NH}_{3}$, which dissociates according to the equation $\mathrm{NH}_{3} \rightleftharpoons \frac{1}{2} \mathrm{~N}_{2}+\frac{3}{2} \mathrm{H}_{2}$, show that, at equilibrium,
$$
K=\frac{\sqrt{27}}{4} \frac{\epsilon_{e}^{2}}{1-\epsilon_{e}^{2}} P
$$

Preeti Kumari
Preeti Kumari
Numerade Educator
01:01

Problem 3

Starting with $n_{0}$ moles of $\mathrm{CO}$ and $3 n_{0}$ moles of $\mathrm{H}_{2}$, which react according to the equation $\mathrm{CO}+3 \mathrm{H}_{2} \rightleftharpoons \mathrm{CH}_{4}+\mathrm{H}_{2} \mathrm{O}$, show that, at equilibrium,
$$
K=\frac{4 \epsilon_{e}^{2}\left(2-\epsilon_{e}\right)^{2}}{27\left(1-\epsilon_{\ell}\right)^{4} P^{2}}
$$

Narayan Hari
Narayan Hari
Numerade Educator
04:18

Problem 4

A mixture of $n_{0} v_{1}$ moles of $B_{1}$ and $n_{0} v_{2}$ moles of $B_{2}$ at temperature $T$ and pressure $P$ occupies a volume $V_{0}$. When the reaction
$$
v_{1} B_{1}+v_{2} B_{2} \rightleftharpoons v_{3} B_{3}+v_{4} B_{4}
$$
has come to equilibrium at the same $T$ and $P$, the volume is $V_{e}$. Show that
$$
\epsilon_{e}=\frac{V_{e}-V_{0}}{V_{0}} \frac{v_{1}+v_{2}}{v_{3}+v_{4}-v_{1}-v_{2}}
$$

David Collins
David Collins
Numerade Educator
03:45

Problem 5

$$
\epsilon_{e}=\frac{V_{e}-V_{0}}{V_{0}} \frac{v_{1}+v_{2}}{v_{3}+v_{4}-v_{1}-v_{2}}
$$

Sherrie Fenner
Sherrie Fenner
Numerade Educator
10:55

Problem 6

The equilibrium constant of reaction $\mathrm{SO}_{3} \rightleftharpoons \mathrm{SO}_{2}+{ }_{2} \mathrm{O}_{2}$ has the following values:
Kelvin temperature $\begin{array}{lllll}\text { perature } & 800 & 900 & 1000 & 1105 \\ \text { n constant } & 0.0319 & 0.153 & 0.540 & 1.59\end{array}$ Equilibrium
Determine the average heat of dissociation graphically.

Zubair Abdulla
Zubair Abdulla
Numerade Educator
04:46

Problem 7

Calculate the degree of ionization of cesium vapor at $10^{-6} \mathrm{~atm}$ at the two temperatures $2260 \mathrm{~K}$ and $2520 \mathrm{~K}$.

Charles Thomas
Charles Thomas
Numerade Educator
01:45

Problem 8

Calculate the degree of ionization of calcium vapor in the sun's chromosphere. The temperature and pressure of the sun's chromosphere are approximately $6000 \mathrm{~K}$ and $10^{-10}$ atm, respectively.

Manik Pulyani
Manik Pulyani
Numerade Educator
07:29

Problem 9

(a) Show that
$$
\Delta G=\Delta H+T\left(\frac{\partial \Delta G}{\partial T}\right)_{\dot{P}}
$$
(b) Show that
$$
\Delta G=-R T \ln \frac{x_{3}^{n_{3}} x_{4}^{n_{4}}}{x_{1}^{n_{1}} x_{2}^{n_{2}}}
$$
where the $x$ 's are equilibrium values.

Krish Desai
Krish Desai
Numerade Educator
00:48

Problem 10

Calculate the heat capacity of the equilibrium mixture of Prob. $16.7$ at the temperature of $2260 \mathrm{~K}$.

Ayushi Sambyal
Ayushi Sambyal
Numerade Educator
01:42

Problem 11

When $1 \mathrm{~mol}$ of HI dissociates according to the reaction
$$
\mathrm{HI} \rightleftharpoons \frac{1}{2} \mathrm{H}_{2}+{ }_{2} \mathrm{I}_{2}
$$
at $T=675 \mathrm{~K}, K=0.132$ and $\Delta H=2950 \mathrm{~J} / \mathrm{mol}$. Calculate $\left(\partial \boldsymbol{\varepsilon}_{e} / \partial T\right)_{P}$ at this tem-
perature.

John Nicolle
John Nicolle
Numerade Educator
03:42

Problem 12

Starting with $v_{1}$ moles of $B_{1}$ and $v_{2}$ moles of $B_{2}$, show that:
(a) At any value of $\epsilon$,
$$
G=\epsilon\left(v_{3} \mu_{3}+v_{4} \mu_{4}-v_{1} \mu_{1}-v_{2} \mu_{2}\right)+v_{1} \mu_{1}+v_{2} \mu_{2}
$$
(b) At equilibrium,
$$
G(\min )=v_{1} \mu_{1},+v_{2} \mu_{2}+
$$
where the subscript e denotes an equilibrium value.
(c)
$$
\frac{G-G(\min )}{R T}=\epsilon\left(\ln \frac{x_{3}^{n_{3}} x_{4}^{y_{4}}}{x_{1}^{n_{1}} x_{2}^{v_{2}}}-\ln \frac{x_{3 e}^{n} x_{4}^{v_{e}}}{x_{1 e}^{v_{1}} x_{2 e}^{v_{2}}}\right)+\ln x_{1}^{n} x_{2}^{v_{2}}-\ln x_{1}^{*_{1}} x_{2 e^{-}}^{n}
$$
(d) At $e=0$,
$$
\frac{G_{0}-G(\min )}{R T}=\ln \left(\frac{v_{1}}{v_{1}+v_{2}}\right)^{n_{1}}\left(\frac{v_{2}}{v_{1}+v_{2}}\right)^{n_{2}}-\ln x_{i e}^{v_{1}} x_{2 e^{-}}^{k_{2}}
$$
(e) At $\epsilon=1$,
$$
\frac{G_{1}-G(\min )}{R T}=\ln \left(\frac{v_{3}}{v_{3}+v_{4}}\right)^{n}\left(\frac{v_{4}}{v_{3}+v_{4}}\right)^{n_{4}}-\ln x_{3 e}^{n_{3}} x_{4 e^{+}}^{n_{4}}
$$

Preeti Kumari
Preeti Kumari
Numerade Educator
01:20

Problem 13

In the case of the ionization of a monatomic gas, show that:
$(a)$
$\frac{G-G(\min )}{R T}=\epsilon\left(\ln \frac{\epsilon^{2}}{1-\epsilon^{2}}-\ln \frac{\epsilon_{e}^{2}}{1-\epsilon_{e}^{2}}\right)+\ln \frac{1-\epsilon}{1+\epsilon}-\ln \frac{1-\epsilon_{e}}{1+\epsilon_{e}}$
(b) At $\epsilon=0$
$$
\frac{G_{0}-G(\mathrm{~min})}{R T}=-\ln \frac{1-\epsilon_{e}}{1+\epsilon_{e}}
$$
(c) At $\epsilon=1$,
$$
\frac{G_{1}-G(\min )}{R T}=\ln \frac{1}{4}-\ln \frac{\epsilon_{e}^{2}}{\left(1+\epsilon_{e}\right)^{2}}
$$
(d) Plot [G-G(min)]/2.30 RT against $\epsilon$ for the ionization of cesium vapor at $2260 \mathrm{~K}$ and $10^{-6} \mathrm{~atm}$, using the result of Prob. $16.7$

Lottie Adams
Lottie Adams
Numerade Educator
01:21

Problem 14

(a) Prove that, for a mixture of reacting ideal gases,
$$
\frac{d}{d \epsilon} \ln \frac{x_{3}^{v_{3}} x_{4}^{v_{4}}}{x_{1}^{h} x_{2}^{v_{2}}}=\frac{n_{0}+n_{0}^{\prime}}{\sum n_{j}} \frac{1}{\psi}
$$
where $\frac{1}{\psi}=\frac{v_{1}^{2}}{x_{1}}+\frac{v_{2}^{2}}{x_{2}}+\frac{v_{3}^{2}}{x_{3}}+\frac{v_{4}^{2}}{x_{4}}-(\Delta v)^{2}$
and $\quad \Delta v=v_{3}+v_{4}-v_{1}-v_{2}$.
(b) If we start with $n_{0} v_{1}$ moles of $B_{1}$ and $n_{0} v_{2}$ moles of $B_{2}$, and no $B_{3}$ or $B_{4}$, show that
$$
\psi=\frac{\epsilon(1-\epsilon)}{\left(v_{1}+v_{2}\right)\left(v_{3}+v_{4}\right)}
$$

Ajay Singhal
Ajay Singhal
Numerade Educator
32:10

Problem 15

Prove that, for a mixture of reacting ideal gases in equilibrium,
$(a)$
$\left(\frac{\partial V}{\partial P}\right)_{T}=-\frac{V}{P}-\frac{\left(n_{0}+n_{0}^{\prime}\right) R T(\Delta \nu)^{2}}{P^{2}\left(d / d \epsilon_{\ell}\right) \ln \left(x_{3}^{1} x_{4}^{2 / 4} / x_{1}^{\nu /} x_{2}^{\prime 2}\right)}$
(b) $\quad\left(\frac{\partial V}{\partial T}\right)_{P}=\frac{V}{T}+\frac{\left(n_{0}+n_{0}^{\prime}\right) \Delta \nu \Delta H}{P T\left(d / d \epsilon_{e}\right) \ln \left(x_{3}^{n} x_{4}^{\nu 4} / x_{1}^{4} x_{2}^{h 2}\right)} .$
(c) $\quad\left(\frac{\partial P}{\partial T}\right)_{4}=-\frac{P \Delta H}{R T^{2} \Delta \nu}$.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
02:46

Problem 16

Prove that, for a mixture of reacting ideal gases in equilibrium,
$$
d S=\sum n_{j}\left[\sum x_{j} c_{P_{j}}+\frac{\psi(\Delta H)^{2}}{R T^{2}}\right] \frac{d T}{T}-R \sum n_{j}\left[1+\frac{\psi \Delta H \Delta \nu}{R T}\right] \frac{d P}{P}
$$
where $\psi$ is given in Prob. $16.14$.

Stephen Ho
Stephen Ho
Numerade Educator