1. The problem statement, all variables and given/known data Consider the system CO2(g) + H2(g) <====> CO(g) + H2O(g) Initially, 0.25 mol of water vapour and 0.2 mol of carbon monoxide are placed in a 1.00 L reaction vessel. At equilibrium, spectroscopic evidence shows that 0.1 mol of carbon dioxide is present. Calculate K for the reaction. 2. Relevant equations equilibrium law 3. The attempt at a solution So writing down the equilibrium law we get. Kc = [CO][H2O]/[CO2][H2] Now we need to find the unknowns. We know 3/4 of the reaction's concentrations but how do you find the forth? An ice table wont work since we don't have a Kc value and without a given H2 value we can't calculate Kc. Stoichometry sounds useless since the system is in equilibrium so what the heck. How do you solve this problem?