Question

Please show step-by-step work. Thank you!

2. The molar solubility of PbBr is 2.17 x 10 M at a certain temperature. Calculate Kp for PbBr. (7)

Answer 1

The is soluble in hot water.Its solubility equilibrium is given by-

PbBrz

$PbBr_{2}_{(s)}\rightleftharpoons Pb^{2+}_{(aq)}+2Br^{-}_{(aq)}$

Now the Solubility product constant of the above solubility equilibrium is given by-

$K_{sp}=[Pb^{2+}].[Br^{-}]^{2}$---1

If the Molar Solubility of the salt is 'S" (say),then from equation 1,we get,

$K_{sp}=S.(2S)^{2}=S.4S^{2}=4S^{3}$

Given that, ,we get-

S = 2.17 × 10-3M

$K_{sp}=4.(2.17\times 10^{-3})^{3}=4.09\times 10^{-8}$.