Chemistry
posted by Linda .
For the system CaO(s) + CO2(g) = CaCO3(s), I added 1.00 mol of CaO(s) to 1.00L of 0.500M CO2(g) at 200C. At equilibrium the [CO2] = 0.150M. What is the value of Kp for this reaction?
A. 0.172 B. 0.150 C. 5.82 D. 6.67 E. 2.59

Kp = pCO2

so would the answer be B?

No, and I gave you the wrong information because I didn't see an arrow sign and I though the CO2 was a product. It isn't, it's a reactant. Therefore,
Kp = 1/pCO2.
You need to find the partial pressure of the CO2 which you can do from PV = nRT.
You know V= 1L, you know R, T is 473K and n = number of mols. Since (CO2) = 0.150M and you have 1L, that is M x L = 0.150 moles. Substitute into PV = nRT and solve for pCO2. Then the reciprocal will give you Kp. 
I get answer 0.172. Is that correct?