Chemistry Reaction Equilibrium help??

Question

0.7 mol of A(g), 0.5 mil of B(g), 0.4 mol of C(g) and 0.9 mol of D(g) were placed in a one litre vessel and allowed to come to equilibrium according to the following equation : A(g) + B(g) ⇔ C(g) + D(g), K=0.5. Calculate The equilibrium concentration of all species present.

Answer 1

A(g) + B(g) <==> C(g) + D(g)

Keq = [C][D]/[A][B] = 0.5

Calculate Q: Q = (0.4)(0.9)/(0.7)(0.5) = 1.0. Since Q is > Keq, reaction will proceed toward reactants.

Setting up an ICE table ...

A(g) + B(g) <==> C(g) + D(g)

0.7......0.5..............0.4.........0.9......I

+x......+x.............-x...........-x.........C

0.7+x..0.5+x......0.4-x......0.9-x.....E

Plug these equilibrium concentrations into the Keq equation = 0.5 and use the quadratic to solve for x, refer to the last line in the ICE table, and calculate final concentrations.

So, e.g. to get [A], add x to 0.7; to get [B], add x to 0.5, etc.