## Chemical Equilibrium Questions and Answers Part-3

1. For the reversible reaction, $N_{2}\left(g\right)+3H_{2}\left(g\right)\rightleftharpoons2NH_{3}\left(g\right)$      at 500°C, the value of $K_{P}$ is $1.44*10^{-5}$   when partial pressure is measured in atmospheres. The corresponding value of Kc, with concentration in mole litre-1, is
a) $\frac{1.44*10^{-5}}{\left(0.082*500\right)^{-2}}$
b) $\frac{1.44*10^{-5}}{\left(8.314* 773\right)^{-2}}$
c) $\frac{1.44*10^{-5}}{\left(0.082 *773\right)^{2}}$
d) $\frac{1.44*10^{-5}}{\left(0.082 *773\right)^{-2}}$

Explanation: $\frac{1.44*10^{-5}}{\left(0.082 *773\right)^{-2}}$

2. For the reaction $C\left(s\right)+CO_{2}\left(g\right)\rightleftharpoons2CO\left(g\right)$     , the partial pressures of $CO_{2}$ and CO are 2.0 and 4.0 atm respectively at equilibrium. The $K_{P}$ for the reaction is.
a) 0.5
b) 4.0
c) 8.0
d) 32.0

Explanation: 8.0

3. The reaction quotient (Q) for the reaction
$N_{2}\left(g\right)+3NH_{3}\left(g\right)\rightleftharpoons2NH_{3}\left(g\right)$
is given by $Q=\frac{\left[NH_{3}\right]^{2}}{\left[N_{2}\right]\left[H_{2}\right]^{3}}$   . The reaction will proceed from
a) $Q<K_{C}$
b) $Q>K_{C}$
c) $Q=0$
d) $Q=K_{C}$

Explanation: $Q>K_{C}$

4. $\triangle G^{\circ}$ for the reaction $X+Y\rightleftharpoons Z$   is –ve 4.606 kcal. The equilibrium constant for the reaction at 227°C is
a) 100
b) 10
c) 2
d) 0.01

Explanation: 100

5. On increasing the pressure, in which direction will the gas phase reaction proceed to re-establish equilibrium, is predicted by applying the Le Chatelier’s principle. Consider the reaction. $N_{2}\left(g\right)+3H_{2}\left(g\right)\rightleftharpoons2NH_{3}\left(g\right)$      Which of the following is correct, if the total pressure at which the equilibrium is established, is increased without changing the temperature?
a) K will remain same
b) K will decrease
c) K will increase
d) K will increase initially and decrease when pressure is very high

Explanation: K will remain same

6. In which of the following reactions, the equilibrium remains unaffected on addition of small amount of argon at constant volume?
a) $H_{2}\left(g\right)+I_{2}\left(g\right) \rightleftharpoons 2HI\left(g\right)$
b) $PCl_{5}\left(g\right)\rightleftharpoons PCl_{3}\left(g\right) Cl_{2}\left(g\right)$
c) $N_{2}\left(g\right)+3H_{2}\left(g\right) \rightleftharpoons 2NH_{3}\left(g\right)$
d) The equilibrium will remain unaffected in all the three cases

Explanation: The equilibrium will remain unaffected in all the three cases

7. Which of the following statements is incorrect?
a) In equilibrium mixture of ice and water kept in perfectly insulated flask mass of ice and water does not change with time.
b) The intensity of red colour increases when oxalic acid is added to a solution containing iron (III) nitrate and potassium thiocyanate.
c) On addition of catalyst the equilibrium constant value is not affected.
d) Equilibrium constant for a reaction with negative $\triangle H$  value decreases as the temperature increases

Explanation: The intensity of red colour increases when oxalic acid is added to a solution containing iron (III) nitrate and potassium thiocyanate.

8. Which is a reversible reaction?
a) $H_{2}+I_{2}\rightarrow 2HI$
b) $H_{2}SO_{4}+Ba\left(OH\right)_{2}\rightarrow BaSO_{4}\downarrow+2H_{2}O$
c) $NaCI+AgNO_{3}\rightarrow NaNO_{3}+AgCl\downarrow$
d) $2KClO_{3}\rightarrow 2KCl+3O_{2}\uparrow$

Explanation: The product is separated as solid or escapes as gas in an irreversible reaction

9. The standard state Gibb's free energy change for the isomerisation reaction
cis-2-pentene $\rightleftharpoons$ trans-2-pentene is –3.67 kJ mol-1 at 400 K. If more trans-2-pentene is added to the reaction vessel
a) more cis-2-pentene is formed
b) equilibrium shifts in the forward direction
c) equilibrium remains unaltered
d) more trans-2-pentene is produced

Explanation: $\triangle$G = 0 at equilibrium