Question

6. Answer the following questions regarding the equilibrium for the reaction below 2 AsH3(g) = 2 As (s) + 3 H2 (9) a. If AsH3 was removed from the equilibrium mixture, what would happen to the equilibrium concentration of H2? (increase, decrease, no change) b. If additional As is added to the reaction, what would happen to the equilibrium concentration of AsH3? (increase, decrease, no change) c. If the value of K decreases as the temperature of the system is decreased, is the reaction endothermic or exothermic? d. Which direction would the reaction shift if the volume of the container was decreased? (forward, reverse, no change) e. If the pressure of the system was increased by adding the non-reactive gas N2 (while volume stays constant), which direction would the reaction shift? (to the left, to the right, no change)

Answer 1

a)Equilibrium concentration of H2 decreases.

According to Le chatelier's principle ,when AsH3 is removed from the equlibrium mixture the system tries to maintain Equilibrium by shifting the reaction toward left(reverse reaction).Hence concentration of H2 decreases

b) Concentration of AsH3 increases

If additional As is added , the equlibrium shift to left .Hence more AsH3 is formed

c)Exothermic reaction

If temperature is decreased , the equlibrium will shift to favour the reaction which increases the temperature.Hence the reaction is exothermic

d) Reaction shifts to reverse direction.

When volume of the container is decreased, pressure increases.Hence equlibrium will shift to reverse direction because there are fewer gaseous molecules on the reactant side which lowers the pressure.

e)No change

When a non reactive N is added to equlibrium at constant volume, the pressure increases but number of moles per unit volume remains same.Hence equlibrium does not change.