alleryStart learning →For CaO(s) + CO2(g) forming CaCO3(s), what is the equilibrium constant expression Kc?
AKc = [CaCO3] / ([CaO] x [CO2])
BKc = [CO2] on its own in the expression
CKc = 1 / [CO2] on its own here
DKc = [CaCO3] / [CO2] for this system
Answer & Solution
Correct answer: C. Kc = 1 / [CO2] on its own here
1. Calcium oxide and calcium carbonate are both pure solids, so both are left out.
2. That leaves only carbon dioxide gas, which sits on the reactant side.
3. A reactant goes in the denominator, so Kc = 1 divided by the carbon dioxide concentration.
4. Options carrying a solid inside the expression break the rule about condensed phases.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 13 "Fundamental Equilibrium Concepts", section 13.2 Equilibrium Constants_
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