PLEASE HELP ME!!! would the CO concentration be decreased or increased??

Question

At 1200 K, the approximate temperature of vehicle exhaust gases, Kp for the reaction

2CO2(g) ⇄ 2CO(g) + O2(g)

is about 1*E-13. Assuming that the exhaust gas (total pressure 1 bar) contains 0.2% CO, 12% CO2 and 3% O2 by volume, is the system at equilibrium with respect to the reaction? Based on your conclusion, would the CO concentration in the exhaust be decreased or increased by a catalyst that speeds up the reaction above?

Answer 1

Your question is somewhat flawed.  A catalyst does not shift an equilibrium, it only allows a system to come to equilibrium more quickly.

For the reaction ...

2CO2(g) ⇄ 2CO(g) + O2(g)

... the Kp is very small, indicating that equilibrium lies far to the left.

If you have a mixture of gases including CO and CO2 where the partial pressure of CO is only about 1/100th the pressure of CO2, the system is not at equilibrium and the system will shift to the left to use up the CO in order to establish equilibrium.

We could calculate Q and compare it to Kp, but since the CO and CO2 concentrations are initially so close, that isn't necessary.

But the catalyst isn't what is shifting the equilibrium, the system will shift anyway.  The catalyst simply makes it shift faster.