Derivation of Kp and Kc

Q.

What is the equilibrium constant dependent on?

Q.

What is the Saha equation?

Q.

Ammonium carbonate decomposes as
$N{H}_{2}COON{H}_4\left(s\right)\leftrightharpoons 2N{H}_3\left(g\right)+C{O}_2\left(g\right)$ For the reaction, $K_P=2.9\times {10}^{-5}at{m}^3$. Calculate the total pressure at equilibrium if $1moleofN{H}_{2}COON{H}_4$is taken.

1. 0.0766 atm

2. 0.0582 atm

3. 0.0388 atm

4. 0.0194 atm

Q. The equilibrium constant at ${25}^{\circ }C$ for the reaction $F{e}^{2+}+A{g}^{+}\rightleftharpoons F{e}^{3+}+Ag$ is:
Given $E_{A{g}^{+}/Ag}^0=0.7998Vand{E}_{F{e}^{3+}/F{e}^{2+}}^0=0.771V$, log 2 =0.30, log 3 = 0.48, $\frac{2.303RT}{F}=0.06$

Q.

What does it mean when ${\mathrm{K}}_{\mathrm{c}}$ is greater than 1.

Q. A weather balloon filled with hydrogen at $1\text{atm}$ and $300\text{K}$ has a volume equal to 12000 litres. On ascending it reaches a place where temperature is $250\text{K}$ and pressure is $0.5\text{atm}$. The volume of the balloon is:

1. 24000 litres
2. 20000 litres
3. 10000 litres
4. 12000 litres

Q. A reaction mixture containing $H_2,N_2$ and $N{H}_3$ has partial pressures 2 atm, 1 atm and 3 atm respectively at 725 K. If the value of $K_p$ for the reaction, $N_{2\left(g\right)}+3H_{2\left(g\right)}\rightleftharpoons 2N{H}_{3\left(g\right)}$ is $4.28\times {10}^{-5}at{m}^{-2}$ at 725 K, in which direction the net reaction will go?

1. Forward
2. Backward
3. No net reaction
4. Direction of reaction cannot be predicted

Q. Consider the following reactions in which all the reactants and products are in gaseous state.
$2PQ\leftrightharpoons P_2+Q_2;K_1=2.5\times {10}^5$
$PQ+\frac{1}{2}{R}_2\leftrightharpoons PQR,K_2=5\times {10}^{-3}$

The value of K₃ for the equilibrium
$1/2P_2+1/2Q_2+1/2R_2\leftrightharpoons PQR$

1. $2.5\times {10}^{-3}$
2. $2.5\times {10}^3$
3. $1.0\times {10}^{-5}$
4. $5\times {10}^3$

Q. When $N_2{O}_5$ is heated at a certain temperature, it dissociates as:
$N_2{O}_5\left(g\right)\rightleftharpoons N_2{O}_3\left(g\right)+O_2\left(g\right);K_c=2.5$. At the same time $N_2{O}_3$ also decomposes as:
$N_2{O}_3\left(g\right)\rightleftharpoons N_2\left(g\right)+O_2\left(g\right);$. If 4.0 moles of $N_2{O}_5$ are taken initially in a 1.0 litre flask and allowed to dissociate, the concentration of $O_2$ at equilibrium is 2.5 M. The equilibrium concentration of $N_2{O}_5$ is :

1. 1.00 M
2. 1.50 M
3. 2.17 M
4. 1.87 M

Q.

The equilibrium constant $k_c$ of the reaction $A_2$ (g) + $B_2$ (g) $\rightleftharpoons$ 2AB (g) is 50. If 1 mol of $A_2$ and 2 mol of $B_2$ are mixed, the amount of AB at equilibrium would be:

1. .934 mol

2. .467 mol

3. 1.4 mol

4. 1.867 mol

Q. For the equilibrium in a closed vessel $PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right),$
$K_p$ is found to be double of $K_c.$ This is attained when:

1. $T=2K$
2. $T=12.18K$
3. $T=24.36K$
4. $T=27.3K$

Q. A flask containing 0.50 atm of ammonia contains some solid $N{H}_{4}HS$ which undergoes dissociation according to $N{H}_{4}HS\left(s\right)\rightleftharpoons N{H}_3\left(g\right)+H_{2}S\left(g\right).$ Calculate the pressure of $N{H}_3$ and $H_{2}S$ at equilibrium $K_P=0.11).$ Also calculate the total pressure.

1. $P_{N{H}_3}$ = 0.6653 atm
   $P_{H_{2}S}$ = 0.1653 atm
   $P_{Total}$ = 0.8306 atm
2. $P_{N{H}_3}$ = 0.2 atm
   $P_{H_{2}S}$ = 0.1 atm
   $P_{Total}$ = 0.3 atm
3. $P_{N{H}_3}$ = 0.1521 atm
   $P_{H_{2}S}$ = 0.1653 atm
   $P_{Total}$ = 0.3174 atm
4. $P_{N{H}_3}$ = 0.5521 atm
   $P_{H_{2}S}$ = 0.0158 atm
   $P_{Total}$ = 0.5679 atm

Q.

What is K in equilibrium?

Q. A reaction at equilibrium involving 2 moles each of $PC{l}_5,PC{l}_3,$ and $C{l}_2$ is maintained at ${250}^{o}C$ and a total pressure of 3 atm. The value of $K_p$ is :
Given: $PC{l}_5\rightleftharpoons PC{l}_3+C{l}_2$

1. 5
2. 4
3. 8
4. 1

Q. $PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$. If 1 mole of $PC{l}_5$ be put in a container of volume V litre and at equilibrium, x moles of it was decomposed, find its $K_p$ and $K_c$ at equilibrium pressure of P atm.

1. $K_c=\frac{x^2}{(1-x)V}$ and $K_P=\frac{x^{2}P}{1-x^2}$
2. $K_c=\frac{x^4}{(1-x)V}$ and $K_P=\frac{x^{4}P}{1-x^2}$
3. $K_c=\frac{x}{(1-x)V}$ and $K_P=\frac{xP}{1-x^2}$
4. None of the above

Q. The equilibrium constant for the reaction $2S{O}_2+O_2\leftrightharpoons 2S{O}_{3}is900at{m}^{-1}at800K.$ A mixture containing $S{O}_{3}and{O}_2$ having initial pressures of $1atmand2atm$ is heated to equilibrate. The partial pressure of $O_2$at equilibrium will be

1. $0.97atm$
2. $0.012atm$
3. $2.01atm$
4. $0.024atm$

Q.

Ammonium carbonate decomposes as
$N{H}_{2}COON{H}_4\left(s\right)\leftrightharpoons 2N{H}_3\left(g\right)+C{O}_2\left(g\right)$ For the reaction, $K_P=2.9\times {10}^{-5}at{m}^3$. Calculate the total pressure at equilibrium if $1moleofN{H}_{2}COON{H}_4$is taken.

1. 0.0766 atm

2. 0.0582 atm

3. 0.0388 atm

4. 0.0194 atm

Q. A vessel at 1000 K contains carbon dioxide with a pressure of 0.5 atm. Some of the carbon dioxide is converted to carbon monoxide on addition of graphite.
$C{O}_2+C\rightleftharpoons 2CO$
Calculate the value of $K_p$ if total pressure at equilibrium is 0.8 atm.

1. 2.5 atm
2. 1.1 atm
3. 0.5 atm
4. 1.8 atm

Q. At ${25}^{0}C$ and 1 atmospheric pressure, the partial pressures in equilibrium mixture of gaseous $N_2{O}_4$ and $N{O}_2$ are 0.7 and 0.3 atm respectively. Calculate the partial pressure of the $N_2{O}_4$ gas when it is in equilibrium ${25}^{o}C$ and the total pressure of 10 atm

1. $9.0atm$
2. $1.0atm$
3. $0.9atm$
4. $0.1atm$

Q. The equilibrium constant for the following reaction is $1.6\times {10}^5$ at $1024K$ $H_2\left(g\right)+B{r}_2\left(g\right)\rightleftharpoons 2HBr\left(g\right)$
Find the equilibrium pressure of $H_2$ gas if $10.0bar$ of $HBr$ is introduced into a sealed container at $1024K$.

1. $2.8\times {10}^3$
2. $5.2\times {10}^{-2}$
3. $2.5\times {10}^{-2}$
4. $3.4\times {10}^{-3}$

Q. $K_c$ for the synthesis of $HI$ (g) from $H_2\left(g\right)$ and $I_2\left(g\right)$ is 50. The degree of dissociation of $HI$ is:
$H_2+I_2\rightleftharpoons 2HI$

1. 0.11
2. 0.54
3. 0.48
4. 0.79

Q. For the reaction, $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$, equilibrium constant $K_C$ is:

1. $\frac{(n_{N{H}_3}{)}^2}{\left(n_{N_2}\right)(n_{H_2}{)}^3}V$
2. $\frac{(n_{N{H}_3}{)}^2}{\left(n_{N_2}\right)(n_{H_2}{)}^3}{V}^2$
3. $\frac{(n_{N{H}_3}{)}^2}{\left(n_{N_2}\right)(n_{H_2}{)}^3}{V}^3$
4. $\frac{(n_{N{H}_3}{)}^2}{\left(n_{N_2}\right)(n_{H_2}{)}^3}$

Q. In the reaction, $C\left(s\right)+C{O}_2\left(g\right)\rightleftharpoons 2CO\left(g\right),$ the equilibrium pressure is 12 atm. If 50% of $C{O}_2$ reacts then $K_p$ will be:

1. 12 atm
2. 16 atm
3. 20 atm
4. 24 atm

Q. In the following gaseous phase equilibrium at constant temperature.
$2S{O}_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2S{O}_3\left(g\right)$
The concentration of $\left[S{O}_2\right]=3.0\times {10}^{-3}M,\left[O_2\right]=3.5\times {10}^{-3}\text{M},\left[S{O}_3\right]=5.0\times {10}^{-2}\text{M}$. Calculate equilibrium constant.

1. $K_c=7.936\times {10}^4$
2. $K_c=17.936\times {10}^4$
3. $K_c=12.936\times {10}^2$
4. $K_c=2.936\times {10}^4$

Q. Hl was heated in a closed tube at ${440}^{\circ }c$ till equilibrium is obtained. At this temperature $22\%$ of Hl was dissociated. The equilibrium constant for this dissociation will be

1. 0.282
2. 0.0796
3. 0.0199
4. 1.99

Q. The expression of $K_C$ for the following reaction is :
$CaC{O}_3\left(s\right)\rightleftharpoons CaO\left(s\right)+C{O}_2\left(g\right)$

1. $K_c=\frac{\left[CaO\right]\times \left[C{O}_2\right]}{\left[CaC{O}_3\right]}$
2. $K_c=\frac{[C{O}_2{]}^2}{\left[CaC{O}_3\right]}$
3. $K_c=\left[C{O}_2\right]$
4. None of the above

Q. The activation energy for a reaction is 25 $kJmo{l}^{-1}$. If the rate of the reaction should be increased 10 times, what should be the temperature to which it should be raised, if the initial temperature is 300 K?

1. 389.6

Q. In a container equilibrium
$N_2{O}_4\left(g\right)\rightleftharpoons 2N{O}_2\left(g\right)$
is attained at ${25}^{o}C.$ The total equilibrium pressure in container is 380 torr. If equilibrium constant of above equilibrium is 0.667 atm, then degree of dissociation of $N_2{O}_4$ at this temperature will be:

1. $\frac{1}{3}$
2. $\frac{1}{2}$
3. $\frac{2}{3}$
4. $\frac{1}{4}$

Q. At some temperature and under a pressure of 4 atm, $PC{l}_5$ is 10% dissociated. Calculated the pressure at which $PC{l}_5$ will be 20% dissociated temperature remaining same.

1. 0.96 atm
2. 0.68 atm
3. 0.54 atm
4. 0.81 atm

Q. The degree of dissociation of $PC{l}_5$ at a certain temperature and pressure= $1atm$ is 0.20. Calculate the value of equilibrium constant $K_p$.

1. $0.084$ atm
2. $0.84$ atm
3. $0.42$ atm
4. $0.042$ atm