Question

Given the reaction A + B ⇌ C and the equilibrium constant, Kc = 2.0 at a certain temperature, if the initial concentration of A is 0.1 M and the initial concentration of B is 0.2 M, what is the equilibrium concentration of C if the reaction proceeds with a rate constant of 0.05 M/s?

Answer 1

To find the equilibrium concentration of C, we can use the equilibrium constant  Kc  expression and an ICE  Initial, Change, Equilibrium  table.The Kc expression for the given reaction is:Kc = [C] /  [A][B] where [A], [B], and [C] are the equilibrium concentrations of A, B, and C, respectively.First, let's set up the ICE table:``          Initial    Change    EquilibriumA         0.1        -x         0.1 - xB         0.2        -x         0.2 - xC          0         +x          x``At equilibrium, the reaction has proceeded to the point where the concentrations of A, B, and C satisfy the Kc expression:2.0 = x /   0.1 - x  0.2 - x  Now we need to solve for x, which represents the equilibrium concentration of C.This is a quadratic equation, but since Kc is not very large, we can make an approximation that x is small compared to the initial concentrations of A and B. Therefore, we can simplify the equation as follows:2.0  x /  0.1 * 0.2 Now, solve for x:x  2.0 * 0.1 * 0.2x  0.04 MSo, the equilibrium concentration of C is approximately 0.04 M.