Solid AgNO3 is added to a solution containing 0.010 M Cl- and 0.010 M Br-. K_sp(AgCl) = 1.6x10^-10, K_sp(AgBr) = 5.0x10^-13. When AgCl just begins to precipitate, what percentage of the original Br- is still in solution? (two decimals)

JEE Main levelNumerical answerDifficulty 2 of 3ia189

Solid $AgNO X_{3}$ is added to a solution containing $0.010 M$ $Cl X^{-}$ and $0.010 M$ $Br X^{-}$ . $K_{s p} (AgCl) = 1.6 \times 1 0^{- 10}$ , $K_{s p} (AgBr) = 5.0 \times 1 0^{- 13}$ . When $AgCl$ just begins to precipitate, what percentage of the original $Br X^{-}$ is still in solution? (two decimals)

Numerical answer type, answer in %, tolerance 0.01.

AgCl

starts at

[Ag X^{+}] = 1.6 \times 1 0^{- 10} /0.010 = 1.6 \times 1 0^{- 8} M

. Then

[Br X^{-}] = 5.0 \times 1 0^{- 13} /1.6 \times 1 0^{- 8} = 3.13 \times 1 0^{- 5} M

, which is

0.31%

0.010 M