Increasing the volume in aqueous equilibria

[sin0001]

Hey,
Suppose you have the following equilibrium: 3A + H20---->  B (aqueous conditions), so upon adding water, would this equilibrium shift to the left and increase the concentration of the aquoeus species or would it remain unchanged?
I recently asked my teacher this question, and she said the latter, but still not convinced :/
Thanks

[daniel034]

The dilution from the addition of water will decrease the concentration more than the shift in equilibrium will make up for. Therefore the concentration of all aqueous species shall be decreased!

[Tonychet2]

i think sin is right, because the concentration of all species is reduced the system favors the reaction that has more particles e.g. net back reaction (equib shifts left)

[stephanieteddy]

So is the water regarded as constant? Because in other situations addition of reactant causes a net shift to the forward reaction, but in the case of dilutions is it that water isn't regarded as a reactant?

[Tonychet2]

water is pretty much constant since its at about 55Molar changing the volume wont really affect the concentration of the water

remember its the change in concentrations that matter !

[stephanieteddy]

Okay, so, are dilutions like increases in volume for gaseous systems? The system will work to partially offset the change by producing more particles? (Is that wording okay btw?)

[Tonychet2]

Okay, so, are dilutions like increases in volume for gaseous systems? The system will work to partially offset the change by producing more particles? (Is that wording okay btw?)

yep

[stephanieteddy]

AWESOME!!!!

[Tonychet2]

but only when ALL the species are increased

[stephanieteddy]

Arigatou!