Pressure and Equilibrium

[EriMizuguchi2K]

I was a little confused on how to go about answering this questions, so if anyone could walk me through it that would be great!

The photosynthesis reaction, 6 CO2(g) + 6 H2O(l) ⇌ C6H12O6(aq) + 6 O2(g), is endothermic. What effect will the following changes have on the equilibrium composition.
a) The partial pressure of CO2 is increased.
b) The partial pressure of CO2 is decreased.

[Joanne Sarsam 2F]

Use Le Chatlier's principle. If the partial pressure of CO2 increases, the partial pressure of O2 and C6H12O6 would increase. If the partial pressure of CO2 decrease, the partial pressure of O2 and C6H12O6 would decrease, to restore equilibrium and maintain the same ratio of products to reactants, aka the same equilibrium constant. Hope this helps.

[Qinyan Feng 1H]

Hi

According to Le Chatlier's principle, the system will resist the change to achieve a new equilibrium. If the partial pressure of CO2 is increased, the system wants to resist this change by decreasing the pressure of CO2, so the reaction will shift to the right. Also, you can have a look at the Q value, if the partial pressure of CO2 increases, Q will now be smaller than K, so the reaction shifts towards forming more products.

Another thing to notice is that in this case, the changing of partial pressure is more like the changing of concentration. It's different from compression or putting in more inert gas.

Hope this helps.

[305607822]

It can be helpful to think of increasing partial pressure like increasing concentration.
If you increase the partial pressure of CO2, you are adding CO2, which means you can form more product. Thus, partial pressure of each of the products increases too.
Similarly, if partial pressure of CO2 decreases, we have less of it, so we can make less product. Then the partial pressure of each product must decrease as well.