Addition or Removal of a Reactant or Product

Question

Some C₆H₅CH₂OH is allowed to dissociate into C₆H₅CHO and H₂ at 523 K. At equilibrium, [C₆H₅CH₂OH] = 0.296 M, and [C₆H₅CHO] = [H₂] = 6.20×10^-2 M. Additional C₆H₅CH₂OH is added so that [C₆H₅CH₂OH]_new = 0.524 M and the system is allowed to once again reach equilibrium. C₆H₅CH₂OH(g) C₆H₅CHO(g) + H₂(g)   K = 1.30×10^-2 at 523 K

In which direction will the reaction proceed to reach equilibrium?

[C₆H₅CHO]

[C₆H₅CH₂OH]

[H₂]

Answer 1

C₆H₅CH₂OH(g) <===> C₆H₅CHO(g) + H₂(g)

Q = [C₆H₅CHO] [H₂] / [C₆H₅CH₂OH]

Q = (0.524) / (0.062)(0.062)

Q = 136

Compared to K of 1.30x10^-2, it is clear that Q is >> K, so reaction will shift to the left toward reactants to reach equilibrium