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Equilibrium Constant and Reaction Quotient At equilibrium, the concentrations of

ID: 1024193 • Letter: E

Question

Equilibrium Constant and Reaction Quotient At equilibrium, the concentrations of reactants and products can be predicted using the equilibrium constant. K_c, which is a mathematical expression based on the chemical equation. For example, in the reaction a A + bB cC + dD where a, b, c, and d are the stoichiometric coefficients, the equilibrium constant is K_c = [c]^c[D]^d/[A]^a[B]^b 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. Q_c. instead of the equilibrium constant. K_c. Q_c = [C]_t^c[D]_t^d/[A]_t^a[B]_t^b where each concentration is measured at some arbitrary time t. A mixture initially contains A, B, and C in the following concentrations: [A] = 0.400 M. [B] = 1.10 M. and [C] = 0.450 M The following reaction occurs and equilibrium is established: A + 2B C At equilibrium. [A] = 0.210 M and [C] = 0.640 M Calculate the value of the equilibrium constant. K_c. Express your answer numerically.

Explanation / Answer

A + 2B ----> C

0.4 1.1 0.45

At equilibrium

0.4-x 1.1-2x 0.45+x

Given ;

0.4 -x = 0.21

x= 0.19

[B] = 1.1 - 2*0.19 = 0.72

K = [C] / [A] [B]^2

Keep all values and evaluate K

K = 5.87