Question

Consider the following exothermic reaction which is used as a source of O2 in some self-contained breathing devices.

4 KO2(s) + 2 CO2(g )⇄ 2 K2CO3(s) + 3 O2(g)

The above reaction is at equilibrium in a closed container. For each of the following changes, indicate whether the reaction will proceed towards products, towards reactants, or have no net reaction to reestablish equilibrium.

a. CO2(g) is added _________________________________

b. O2(g) is removed _________________________________

c. Some K2CO3(s) is removed _________________________

d. The temperature is increased ________________________

e. The reaction is moved to a smaller vessel ______________

f. The pressure is increased by adding N2(g)_______________

g. What general conditions of temperature and pressure favor maximum yield of O2(g)? _______

Answer 1

First, let us state the Le Chatelier principle which deals with changes in an equilibrium:

The statement is as follows:

If any equilibrium is disturbed, that is, change in conditions such as P,T, concentration, partial pressure, etc.., the system will counterbalance such change in order to favour the system's equilbirium.

• Change in concentration
• Change in pressure
• Change in temperature

a)

if we add a reactant, CO2, then the shift goes toward more production of products, so it shifts to the ight

b)

If we remove a product, then the reactants will counterbalnace this via produciton of O2, shift goes to the right

c)

solid removal has no effect in equilibrium

d)

This is exothermic, it releases heat, so increasing T will not favour forward direaciton. The shift goes toward the left

e)

smaller vessel implies MORE pressure. More pressurefavoures the LEAST mol of gses formatin, this is 2 mol of C2 vs 3 mol of O2, so the shift goes to the left

f)

similar as in e, increase in P favours the left side

g)

decrease T and P in order to maximize O2