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J. W. Hill, R. H. Petrucci, T. W. McCreary, & S. S. Perry General Chemistry, 4th edition.

Review Question 14.14.

In which of the following reactions will the amount of product at equilibrium increase if the total gas pressure is raised from 1 atm to 10 atm? Explain.

(a) SO2(g) + Cl2(g)SO2Cl2(g)

(b) N2(g) + O2(g)2 NO(g)

(c) SO2(g) + ½ O2(g)SO3(g)




Answer:

LeChatelier's Principle says that an equilibrium will shift to compensate for any added stress. In this case, the pressure is raised from 1 atm to 10 atm, so each reaction will shift to alleviate that pressure, i.e., towards the side with fewer moles of gases.

(a) SO2(g) + Cl2(g)SO2Cl2(g)

Reactants: 2 moles of gases

Products: 1 mole of gases

An increase in pressure will cause a shift towards products, therefore there will be more product formation at 10 atm.

(b) N2(g) + O2(g)2 NO(g)

Reactants: 2 moles of gases

Products: 2 mole of gases

Both sides have the same number of moles of gases so there will be no shift in the equilibrium.

c) SO2(g) + ½ O2(g)SO3(g)

Reactants: 1 moles of gases

Products: 1.5 mole of gases

An increase in pressure will cause a shift towards products, therefore there will be more product formation at 10 atm.