1. The problem statement, all variables and given/known data For the reaction: A + B ↔ C + D 6.0 moles of A and 5.0 moles of B are mixed together in a suitable container. When equilibrium is reached, 4.0 moles of C are produced. The equilibrium constant for this reaction is: a. K = 1/8 b. K = 8 c. K = 30/16 d. K = 16/30 2. Relevant equations K=[C][D]/[A] 3. The attempt at a solution I set up the problem like this: Initial Concentrations: [A] 6/x 5/x [C] 0 [D] 0 Change in Concentrations: [A] -4/x -4/x [C] +4/x [D] 0 Equlibirum Concentrations: [A] 2/x 1/x [C] 4/x [D] 0 I assigned the variables x myself: x= volume of container The reason I put 0 for D's concentration is b/c the problem did not say any amount of D was formed. Therefore the equilibrium expression should look like this: [4/x]/[2/x^2] which further equates to 2x. I don't where I messed up or how to solve this. Any help would be appreciated. Thanks.