Question

For the following systems at equilibrium

1. CaCO3(s) <-> CaO(s) +CO2 (g) Delta H = +178 kJ/mol
2. PCl3(g) + Cl2(g) <-> PCl5 (g) Delta H= -88 kJ/mol

classify these changes by their effectt

(a) system 1 increase temp:
(b) system1 decrease temp:
(c) system 2 increase temp:
(d) system 2 decrease temp:

Answer 1

1. CaCO3(s) <=> CaO(s) +CO2 (g) Delta H = +178 kJ/mol

Since Delta H is positive, it means the reaction is endothermic

a. An increase in temperature will will shift the equilibrium position to the right, thus forming more products

b. A decrease in the temperature will shift the equilibrium position to the left, thus forming more reactants

2. PCl3(g) + Cl2(g) <-> PCl5 (g) Delta H= -88 kJ/mol

From the above, Delta H is negative which implies exothermic reaction.

c. Increasing the temperature will shift the equilibrium position to the left, thus forming more reactants.

d. Decreasing the temperature will shift the equilibrium position to the right, thus forming more products