Carbon monoxide gas and hydrogen gas are mixed in a two liter flask. The reaction produces methanol gas as the only product. At equilibrium the Keq is 1.1 x 10-5. The flask initially held 6 grams of hydrogen and the equilibrium concentration of hydrogen is 0.1 M. How many grams of carbon monoxide were used?

Answer 1

mols H2 = 6/2 = 3
M H2 = 3mols/2L = 1.5M
.............CO + 2H2 ==> CH3OH
initial......?....1.5M.....0
change......-x.....-2x.....+x
equil......?-x......0.1.....x
H2 started at 1.5 and ended at 0.1; therefore, 2x = 0.7M
0.7M CH3OH produced. 0.7M CO used.
grams = mols x molar mass.