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Equilibrium Constant and Reaction Quotient At equilibrium, the concentrations of

ID: 837745 • Letter: E

Question

Equilibrium Constant and Reaction Quotient At equilibrium, the concentrations of reactants and products can be predicted using the equilibrium constant, Kc, which is a mathematical expression based on the chemical equation. For example, in the reaction where a, b, c, and d are the stoichiometric coefficients, the equilibrium constant is where [A], [B], [C], and [D] are the equilibrium concentrations. If the reaction is not at equilibrium, the quantity can still be calculated, but it is called the reaction quotient, Qc, instead of the equilibrium constant, Kc. where each concentration is measured at some arbitrary time t. A mixture initially contains A, B, and C in the following concentrations: [A] = 0.600M, [B = 0.600M, and [C] = 0.700M. The following reaction occurs and equilibrium is established: At equilibrium, [A] = 0.400M and [C] = 0.900M. Calculate the value of the equilibrium constant, Kc. Express your answer numerically. This question will be shown after you complete previous question(s).

Explanation / Answer

A     + 2 B    = C

0.6       0.6         0.7        initially

0.4        ?          0.9       at equilibrium

As A reacts with B at 1:2 molar ratio, (0.6 - 0.4) = 0.2 M A has reacted with 0.4 M B.

Here, Kc = [C] / [A] [B]2

= 0.9 / 0.4 (0.2)2

= 0.9 / 0.016

= 56.25