Question

Dehydration plays a role in the formation of kidney stones composed of calcium oxalate, CaC₂O₄. Why would increasing a patient's intake of water help reduce the formation of kidney stones?

Answer 1

CaC2O4(s) <--> Ca+2 + C2O4-2

Ksp = [Ca+2][C2O4-2]

First, let us state the Le Chatelier principle which deals with changes in an equilibrium:

The statement is as follows:

If any equilibrium is disturbed, that is, change in conditions such as P,T, concentration, partial pressure, etc.., the system will counterbalance such change in order to favour the system's equilbirium.

• Change in concentration
• Change in pressure
• Change in temperature

Therefore,

if we want to shift from solid CaC2O4 to soluble salt

CaC2O4(s) <--> Ca+2 + C2O4-2

we need to favour shift to the RIGHT side

this is done if we DILUTE the system, that is

if Volume of solution increases

Which is the case if we increas eintake of water

Solubility of ions decreases

so shift must go from solid to aqueous

this way we can decrease solid amount of CaC2O4