Affecting the equilibrium

Question

Hi! I need help with this question:

Consider the following reactions:

1. CO2 (g) + H2O (l) <-> H2CO3 (aq) + heat
2. CaCO3 (s) + H2CO3 (aq) <-> Ca2+ (aq) + 2 HCO3- (aq) + heat

How do you decrease the amount of CaCO3?

My thoughts: I am confused, I thought solids are considered constant in equilibria?? Anyway in order to decrease it I thought we can do in these ways, am I correct?:

1. Increasing H2CO3
2. Cooling down the environment
3. Adding CO2
4. Increasing pressure
5. I am not sure, but does adding water works or not? Isnt it a pure liquid and therefore not counted in equilibrium constant and therefore adding or increasing it will not change how much CaCO3 we have?

Answer 1

For your current answers, I'd agree with (1), (2) and (3), but not sure about (4). Increasing pressure would shift reaction 1 to the right, reducing the CO2 but at the same time, increasing the H2CO3. So this agrees with your #1 but is at odds with your #3.

For (5) you can't really add water on a micro scale. If you just add water you will dilute the entire system and it would have no effect on the equilibrium.