You posted an equation with actions but no question. I assume you want to know which way the reaction shifts (Le Chatelier's Principle).
Here's the way you know. In simple but non-esoteric terms Le Chatelier's Principle says "when a system in equilibrium is exposed to a stress it will shift so as to undo what we've done to it. Keep that in mind.
a) increase [H2]
If you increase H2 it will shift so as to get rid of H2. How can it do that? It can move to the right so as to increase HI, decreasing H2, and decreasing I2 in the process.
b) increase [HI] same logic as a which means it will shift to the left.
c) increase the pressure by lowering the volume
Lowering the volume increases pressure. The reaction will shift to the side with fewer mols of gas for increasing P. Since you have 2 mols gas on the left and 2 mols on the right there will be no shift.
d) add a catalyst Adding or taking away of a catalyst doesn't change the equilibrium so there is no shift. Adding or removing a catalyst affects how FAST equilibrium is reached but it does not affect the POINT of equilibrium.
I love these Le Chatelier's problems. They really are simple to answer but they always give students so much trouble. I never understood why. The answer always is that the equilibrium just "does away what we've done to it".
. H2(g) + I2(g) ↔ 2HI(g) ∆H = +52.7 kJ/mol
a) increase [H2]
b) increase [HI]
c) increase the pressure by lowering the volume
d) add a catalyst
1 answer