At 500 ºC, the decomposition of water into hydrogen and oxygen,

Question

2H2O(g) 2H2(g) + O2(g)

has Kc = 6.0 × 10-28. What are the concentrations of H2 and O2 that are present at equilibrium in a 2.00 L reaction vessel at this temperature if the container originally held 0.086 mol H2O?

Answer 1

(H2O( = 0.0860 mol/2.00L = approx 0.043M

............2H2O --> 2H2 + O2
I..........0.043......0.....0
C...........-2x...... 2x....x
E..........0.043-2x...2x....x

Substitute the E line into the Kc expression and solve for x.