What mass of Ag2CrO4 (molar mass 332 g mol^-1, K_sp = 1.1 x 10^-12) dissolves in 250 mL of 0.020 M K2CrO4? Neglect the chromate contributed by the salt itself. Give the answer in mg (two decimals).

JEE Advanced levelNumerical answerDifficulty 3 of 3ie209

What mass of $Ag X_{2} CrO X_{4}$ (molar mass $332 g mo l^{- 1}$ , $K_{s p} = 1.1 \times 1 0^{- 12}$ ) dissolves in $250 mL$ of $0.020 M$ $K X_{2} CrO X_{4}$ ? Neglect the chromate contributed by the salt itself. Give the answer in mg (two decimals).

Numerical answer type, answer in mg, tolerance 0.02.

[CrO X_{4} X^{2 -}] \approx 0.020 M

, so

[Ag X^{+}] = 1.1 \times 1 0^{- 12} /0.020 = 7.4 \times 1 0^{- 6} M

. Dissolved salt

= [Ag X^{+}] /2 = 3.7 \times 1 0^{- 6} M

. Mass

= 3.7 \times 1 0^{- 6} \times 332 \times 0.250 = 0.31 mg

(after converting g to mg).