Given the following reaction at equilibrium at 450.0 °C: CaCO₃ (s) CaO (s) + CO₂ (g)
If pCO₂ = 0.0155 atm, K_c = ________.

Question

Given the following reaction at equilibrium at 450.0 °C: CaCO₃ (s) CaO (s) + CO₂ (g) If pCO₂ = 0.0155 atm, K_c = ________.

Quizplus · Accepted Answer

The equilibrium constant expression for the given reaction is: 
Kc = ([CaO]/[COS]) × (pCOS) ^n 
where n is the stoichiometric coefficient of COS.
From the balanced chemical equation, we can see that n=1. 
At equilibrium, the concentrations of CaO(s) and COS(g) are solids therefore their concentrations are constant and can be considered as 1. 
Thus, Kc = pCOS = 0.0155 atm. 
Hence, the answer is D.

Given the Following Reaction at Equilibrium at 450