Question

A solution contains 1.32×10-2 M lead nitrate and 1.16×10-2 M copper(II) acetate. Solid sodium carbonate is added slowly to this mixture.

A. What is the formula of the substance that precipitates first? formula =
B. What is the concentration of carbonate ion when this precipitation first begins? [CO32-] = M

Answer 1

CuCO₃ is the formula of the substance that will precipitate out first

the concentration of carbonate ion when this precipitation first begins = 1.212 × 10⁻¹¹ M

Step-by-step explanation:

`Pb(NO_3)_2 \ + \ Na_2CO_3 -----> PbCO_3 \ + \ 2NaNO\\\\ksp \ of \ PbCO_3 = 1.6*10^(-13) \\\\ \\Cu (CH_3COO)_2 \ + \ Na_2CO_3 ------> CuCO_3 \ + \ Na(C_2H_3O_2)\\\\ksp \ of CuCO_3 = 1.3*10^(-10)\\\\As \ ksp \ of CuCO_3 > PbCO_3\\\\Then \ \ CuCO_3 \ will \ precipitate \ out \ first`

`PbCO_3 ----> Pb^(2+)_((aq)) + CO^(2-)_(3(aq))`

`[Pb^(2+)]` will be
`[Pb(NO_3)_2] = 1.32 *10^(-2) \ M`

`ksp = [Pb^(2+)][CO^(2-)_3]`

`1.6*10^(-13) = (1.32*10^(-2))(CO^(2-)_3)\\\\(CO^(2-)_3) = (1.6*10^(-13))/((1.32*10^(-2)))\\\\(CO^(2-)_3) = 1.212 *10^(-11) \ \ M`