Question

Consider this system at equilibrium.

A(aq) <==>B(aq)
Delta H= -550 kL/mol
What can be said about Q and K immediately after an increase in temperature?

a) Q > K because Q increased
b) Q > K because K decreased
c) Q < K because Q decreased
d) Q < K because K increased
e) Q=K because neither changed

How will the system respond to a temperature increase?

1, shift left
2, shift right
3, no change

Answer 1

Q is the "reaction quotient" and is used to determine which way a given system will move to establish equilibrium. If the initial conditions give a Q which is larger than K, then the equilibrium will move to the left to establish equilibrium. If the value of Q is less than the value of K, then the system will move to the right to establish equilibrium. If Q happens to equal K, then the system is at equilibrium.
When equilibrium is re-established the value of K will be greater. Temperature changes are the only changes that actually change the value of K.