alleryStart learning →Liquid bromine evaporates as Br2(l) forming Br2(g). What is the Kc expression for this change?
AKc = [Br2 gas] over [Br2 liquid] here
BKc = [Br2 gas] on its own by itself
CKc = [Br2 liquid] on its own by itself
DKc = 1 over [Br2 gas] for this change
Answer & Solution
Correct answer: B. Kc = [Br2 gas] on its own by itself
1. This is a heterogeneous equilibrium because a liquid and a gas are both present.
2. Liquid bromine is a pure liquid, so it is left out of the expression.
3. Gaseous bromine is the only remaining species, and it is the product.
4. Kc is therefore just the concentration of bromine vapour.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 13 "Fundamental Equilibrium Concepts", section 13.2 Equilibrium Constants_
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