Question

94. Gout-a condition that results in joint swelling and pain-is caused by the formation of sodium urate (NaCsH&N4) crystals within tendons, cartilage, and ligaments. Sodium urate precipi- tates out of blood plasma when uric acid levels become abnor- mally high. This could happen as a result of eating too many rich foods and consuming too much alcohol, which is why gout is sometimes referred to as the "disease of kings." If the sodium concentration in blood plasma is 0.140 M, and Kp for sodium urate is 5.76 x 10-8 what minimum concentration of urate would result in the precipitation of sodium urate? 99 10 101

Answer 1

Note: the molecular formula for sodium urate in the question is missing 3 O atoms.

Sodium Urate will precipitate as follows:

(NaC; H3N403)

Na+ + C5H3N403 + NaC;H3N403(5)

Hence, the equilibrium constant Ksp of the reverse reaction is

Ksp = [Na+]C5H3N403) = 5.76 x 10-

Note that the solid precipitate does not appear on the Ksp equation.

Now, it is given that the blood plasma concentration of Na+ =

Nat] = 0.140 M

Hence, the concentration of urate above which precipitation of sodium urate will occur can be calculated as

[Na+][C5H3N403) = 5.76 x 10-8 5.76 x 10-8 → C5H3N403]= - 4.12 x 10-7 M 0.140

Hence, the minium concentration of urate above which precipitation of sodium urate will occur is
4.12 x 10-7 M
.