Consider the reaction 2 A ⇄ 2 D + E. If K = 5 at Temperature T, which direction will this reaction proceed if [A] = 0.5 M, [D] = 1.5 M and [E] = 0.5 M at temperature T?
2 A ⇄ 2 D + E. K = 5
[A] = 0.5 M, [D] = 1.5 M and [E] = 0.5 M
Q = (E)(D)^2/(A)^2
Q = (0.5)(1.5)^2/(0.5)^2 = 4.5
Q < K so reaction will proceed to the right. Actually I have trouble remembering the Q and K so I do it this way.
K is 5 and Q is 4.5. Q is less which means products are too small and reactants are too large. Therefore, products must get larger and reactants must get smaller which means rxn proceeds to the right.