Chem Help Please?

Question

Compound A decomposes according to the equation below.

A(g) <~> 2 B(g) + C(g)


A sealed 1.00 L reaction vessel initially contains 1.77 10-3 mol A(g), 1.26 10-3 mol B(g), and 6.09 10-4 mol C(g) at 100°C . When equilibrium is reached, the concentration of A(g) is 2.15 10-3 M. What are the equilibrium concentrations of B(g) and C(g)?

B(g) ____ M

C(g) ____ M

Answer 1

Since A gained concentration, B and C had to go down, and in stoichiometric ratio to A. As A gained 0.38 * 10^-3 M, B had to lose 0.76 * 10^-3 M and C had to lose 0.38 * 10^-3 M. So B = 0.50 * 10^-3 or 5.00 * 10^-4 M and C = 2.29 * 10^-4 M.