1.00 mol of A is placed in a 1.00 L container and A(g) <=> 2B(g) reaches equilibrium with [B] = 0.40 M. What is the equilibrium constant?
Answer and explanation
Correct answer: D. 0.20
- Step 1: B at equilibrium is 0.40 M, so 0.20 mol of A has reacted (ratio 1 : 2).
- Step 2: [A] = 1.00 - 0.20 = 0.80 M.
- Step 3: K = [B]^2 / [A] = 0.16 / 0.80 = 0.20.
Answer
0.20.
Why not the others: 0.16 is [B]^2 alone; 0.50 and 0.80 use [A] = 0.50 or confuse [A] with K.
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