What is the effect of adding more water to the following reaction?
CO2 + H2O <--> H2CO3
a. more H2CO3 is produced
b. CO2 concentration increases
c. nothing

Hi again teatea!
The answer is 'c': nothing. We can show that both 'a' and 'b' are
false, therefore the answer must be 'c'.

It's not true that moer H2CO3 is produced. Notice that H2CO3 has one
carbon atom (C). Since you are only adding water (H2O), there's no
more carbon to produce more H2CO3. It's also not true that the
concentration of CO2 increases. The concentration of a substance is
measured as moles/liter (moles of the substance per liter of water).
Since you are adding more water, there are more liters, but the same
amount of moles of CO2 (because you're not adding CO2). Therefore, CO2
concentration also can't increase. The correct answer must then be
'c'.

I hope this helps! If you have any doubts regarding my answer, please
request a clarification before rating it. Otherwise I await your
rating and final comments.


Best wishes!
elmarto

Actually, teatea-ga, your chemistry is dead wrong. The correct answer
is 'a'. A stress on an equilibrium reaction shifts the equilibrium
away from the stress. As more H2O is added the equilibrium deals with
the excess by forming more of the product.

"Since you are only adding water (H2O), there's no more carbon to
produce more H2CO3"

Nope. Equilibrium reactions don't go to completion and eliminate all
of the reactants. There is always a some of the reactants left over
depending on the equilibrium constant.

Sorry, I misread teatea as the answerer. No, elmarto-ga is the one
with the bad chemistry. You're just confused now :(.

Darthcow is right. It's called Le Chatelier's Principe. You can look
it up in any basic chemistry book.