Question

Describe the effect on the concentration of the bold substance by the following change: decrease the volume

The equilibrium is: 2HF(g) <--> F2(g) + H2; change in H=536KJ

F2(g) is bolded.

Shouldn't F2(g) increase when voume is decreased? Why is there no change?

Thanks in advance.

Answer 1

you actually left out something very important:
2HF(g) <--> F2(g) + H2(g)
Hydrogen is a gas.
Notice that you have two volumes on the left, two volumes on the right at equilibrium. So reducing volume on both sides will have no effect on equilibrium.

Answer 2

So I have to count the number of gaseous molecules first? Thanks!