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Question:

Given the reaction between 2 gases represented by A2 and B2 to give the compound AB(g). A2(g) + B2(g)⇌2AB(g) At equilibrium, the concentration of A2 = 3.0 × 10⁻⁷ M of B2 = 4.2 × 10⁻⁷ M of AB = 2.8 × 10⁻⁷ M If the reaction takes place in a sealed vessel at 527oC, then the value of Kc will be:

1.9

2.0

0.62

4.5

Solution:

The equilibrium reaction is as given below.
A2 + B2 ⇌ 2AB
The expression for the equilibrium constant is as given below.
Kc = [AB]²/([A2][B2])
Substitute values in the above expression.
Kc = (2.8 × 10⁻⁷)²/(3.0 × 10⁻⁷ × 4.2 × 10⁻⁷) = 0.62.
Hence, the value of the equilibrium constant is 0.62.