Question

1. Many kidney stones contain calcium oxalate crystals that have separated from the urine. Suppose you've developed kidney stones, and your doctor has determined they are mainly made of CaC₂O₄.

a. The first "prescription" is likely to be, "Drink lots of water." How might this help?

b. The second piece of advice might be, "Don't eat too much rhubarb pie!" (And also chocolate, coffee, peanut butter, strawberries, spinach...) Speculate a reason for this advice.

c. Knowing acid/base chemistry, you ask your doctor whether a drop in your urine's pH might help dissove the kidney stone. Why is this a reasonable question to ask? (By the way, the answer is, "No, it's more complicated than that...")

Answer 1

a)

CaC2O4 <-> Ca+2+ C2O4-2

clearly, as the system becomes diluted, Ca+2 and C2O4-2 decreases in solubility

which make sthe solid CaC2O4 to increase in ionic, Ca+2 and C2O4-2 to counterbalance the loss

therefore, solid goes into solution

b)

most likely because they are rich in oxalates, i.e. C2O4-2

if we increase C2O4-2 in the reaction, the shift must go towards more formation of CaC2O4(s)

c)

if we decrease pH, then H+ increase sin blood

this might help into:

H+ + C2O4-2 <--> HC2O4-

is C2O4-2 is consumed, then solid CaC2O4 must go towards solution, i.e. solids disspear