Question

A platinum catalyst is used in automobile catalytic converters to hasten the oxidation of carbon monoxide:
2CO(g)+O2(g)⇌Pt2CO2(g)ΔH∘=−566kJ
Suppose that you have a reaction vessel containing an equilibrium mixture of CO(g), O2(g), and CO2(g). Under the following conditions, will the amount of CO increase, decrease, or remain the same after each of the following changes?

Part A

A platinum catalyst is added.

A platinum catalyst is added.

	increase
	decrease
	remain the same

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Part B

The temperature is increased.

The temperature is increased.

	increase
	decrease
	remain the same

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Part C

The pressure is increased by decreasing the volume.

The pressure is increased by decreasing the volume.

	increase
	decrease
	remain the same

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Part D

The pressure is increased by adding argon gas.

The pressure is increased by adding argon gas.

	increase
	decrease
	remain the same

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Part E

The pressure is increased by adding O2 gas.

The pressure is increased by adding  gas.

	increase
	decrease
	remain the same

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Answer 1

The equilibrium is

2CO(g)+O2(g) ⇌ 2CO2(g)         ΔH∘=−566kJ

a) Platinum is added: there will be no effect on equilibrium due to addition of catalyst hence the concentration of CO will remains the same

b) Temperature is increased: As enthalpy of reaction is negative, the reaction is exothermic hence on increasing temperature the reaction will move backwards, hence concentration of reactants will increase

Concentration of CO will increase

c) The moles of gas is more on reactant side

If pressure is increased, volume will decrease hence the concentration will increase. To balance the equilibrium will move in forward direction (less moles of gas) hence the concentration of products will decrease

Concentration of CO will decrease

d) On adding inert gas, no change in concentration of CO

e) WE are adding reactant (O2) the concentration of CO will decrease