1. The problem statement, all variables and given/known data Equal Volumes of 3.60 M A2+ and 6.80 M B- are mixed. After the reaction, equilibrium is established with [B-] = 0.40 M. What is the [A2+] at equilibrium? 2. Relevant equations Ice table, algebra 3. The attempt at a solution This is probably a really easy problem, but I seem to be getting the wrong answer. Probably just a small lapse, but anyways, here's my work. Equilibrium constant not given. Ice Table: A2+ (aq) + 3B- ==><== AB3- I 3.60 6.80 0 C +x -3x +x E 3.60 - x 0.40 +x By subtracting 0.40 from 6.80, I determined 3x to be 6.4. Using the ratios, I divided 3x by 3 to get 2.13(3 repeating). Next I subtracted x from 3.60, and got my answer or 1.47. The answer key says I am wrong, and that [A2+] at equilibrium is 0.80 M. So am I going about this wrong, or is the book wrong (it has been in the past)? Thanks!