Factors affecting equilibrium; Le Chatelier's principle — practice questions

Question 1 · difficulty L2 · understanding

The number of correct statement/s involving equilibria in physical processes from the following is ________ (A) Equilibrium is possible only in a closed system at a given temperature. (B) Both the opposing processes occur at the same rate. (C) When equilibrium is attained at a given temperature, the value of all its parameters became equal. (D) For dissolution of solids in liquids, the solubility is constant at a given temperature.

Question 2 · difficulty L2 · understanding

Consider the following equation: $2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{SO}_{3}(g), \Delta H=-190 \mathrm{~kJ}$ The number of factors which will increase the yield of $\mathrm{SO}_{3}$ at equilibrium from the following is _______. A. Increasing temperature B. Increasing pressure C. Adding more $\mathrm{SO}_{2}$ D. Adding more $\mathrm{O}_{2}$ E. Addition of catalyst

Question 3 · difficulty L2 · understanding

Consider the reaction, A $$\rightleftharpoons$$ B at 1000 K. At time t', the temperature of the system was increased to 2000 K and the system was allowed to reach equilibrium. Throughout this experiment the partial pressure of A was maintained at 1 bar. Given, below is the plot of the partial pressure of B with time. What is the ratio of the standard Gibbs energy of the reaction at 1000 K to that at 2000 K?

Question 4 · difficulty L2 · understanding

The following reaction occurs in the Blast furnance where iron ore is reduced to iron metal $$\mathrm{Fe}_2 \mathrm{O}_{3(s)}+3 \mathrm{CO}_{(g)} \rightleftharpoons \mathrm{Fe}_{(\mathrm{l})}+3 \mathrm{CO}_{2(g)}$$ Using the Le-chatelier's principle, predict which one of the following will not disturb the equilibrium.

• A. Addition of $$\mathrm{CO}_2$$
• B. Removal of $$\mathrm{CO}$$
• C. Addition of $$\mathrm{Fe}_2 \mathrm{O}_3$$
• D. Removal of $$\mathrm{CO}_2$$

Question 5 · difficulty L2 · understanding

Higher yield of NO in $\mathrm{N}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})$ can be obtained at $\left[\Delta \mathrm{H}\right.$ of the reaction $\left.=+180.7 \mathrm{~kJ} \mathrm{~mol}^{-1}\right]$ A. Higher temperature B. Lower temperature C. Higher concentration of $\mathrm{N}_2$ D. Higher concentration of $\mathrm{O}_2$ Choose the correct answer from the options given below :

• A. B, C, D only
• B. A, C, D only
• C. A, D only
• D. B, C only

Question 6 · difficulty L3 · understanding

At 298 K $$\mathrm{N_2~(g)+3H_2~(g)\rightleftharpoons~2NH_3~(g),~K_1=4\times10^5}$$ $$\mathrm{N_2~(g)+O_2~(g)\rightleftharpoons~2NO~(g),~K_2=1.6\times10^{12}}$$ $$\mathrm{H_2~(g)+\frac{1}{2}O_2~(g)\rightleftharpoons~H_2O~(g),~K_3=1.0\times10^{-13}}$$ Based on above equilibria, then equilibrium constant of the reaction, $$\mathrm{2NH_3(g)+\frac{5}{2}O_2~(g)\rightleftharpoons~2NO~(g)+3H_2O~(g)}$$ is ____________ $$\times10^{-33}$$ (Nearest integer).

Question 7 · difficulty L3 · understanding

40% of HI undergoes decomposition to H 2 and I 2 at 300 K. $$\Delta$$G$$^\Theta$$ for this decomposition reaction at one atmosphere pressure is __________ J mol $$-$$1 . [nearest integer] (Use R = 8.31 J K $$-$$1 mol $$-$$1 ; log 2 = 0.3010, ln 10 = 2.3, log 3 = 0.477)

Question 8 · difficulty L3 · understanding

Consider the following gaseous equilibrium in a closed container of volume ' $V$ ' at $\mathrm{T}(\mathrm{K})$. $$\mathrm{P}_2(\mathrm{~g})+\mathrm{Q}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{PQ}(\mathrm{~g})$$ 2 moles each of $\mathrm{P}_2(\mathrm{~g}), \mathrm{Q}_2(\mathrm{~g})$ and $\mathrm{PQ}(\mathrm{g})$ are present at equilibrium. Now one mole each of ' $\mathrm{P}_2$ ' and ' $\mathrm{Q}_2$ ' are added to the equilibrium keeping the temperature at $\mathrm{T}(\mathrm{K})$. The number of moles of $\mathrm{P}_2, \mathrm{Q}_2$ and PQ at the new equilibrium, respectively, are

• A. $2.56,1.62,2.24$
• B. $2.67,2.67,2.67$
• C. 1.21, 2.24, 1.56
• D. $1.66,1.66,1.66$

Question 9 · difficulty L3 · understanding

In the following system, $\mathrm{PCl}_5(\mathrm{~g}) \leftrightharpoons \mathrm{PCl}_3(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g})$ at equilibrium, upon addition of xenon gas at constant T \& p , the concentration of

• A. $\mathrm{PCl}_5, \mathrm{PCl}_3 \& \mathrm{Cl}_2$ remain constant
• B. $\mathrm{PCl}_3$ will increase
• C. $\mathrm{Cl}_2$ will decrease
• D. $\mathrm{PCl}_5$ will increase

Question 10 · difficulty L3 · understanding

Consider the equilibrium $$\mathrm{CO}(\mathrm{g})+3 \mathrm{H}_2(\mathrm{~g}) \rightleftharpoons \mathrm{CH}_4(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{~g})$$ If the pressure applied over the system increases by two fold at constant temperature then (A) Concentration of reactants and products increases. (B) Equilibrium will shift in forward direction. (C) Equilibrium constant increases since concentration of products increases. (D) Equilibrium constant remains unchanged as concentration of reactants and products remain same. Choose the correct answer from the options given below :

• A. (A) and (B) only
• B. (A), (B) and (D) only
• C. (B) and (C) only
• D. (A), (B) and (C) only