15.1 Precipitation and dissolution  (Page 12/17)

Perform the following calculations:

(a) Calculate [Ag ⁺ ] in a saturated aqueous solution of AgBr.

(b) What will [Ag ⁺ ] be when enough KBr has been added to make [Br ^– ] = 0.050 M ?

(c) What will [Br ^– ] be when enough AgNO ₃ has been added to make [Ag ⁺ ] = 0.020 M ?

The solubility product of CaSO ₄ ·2H ₂ O is 2.4 $\times$ 10 ^–5 . What mass of this salt will dissolve in 1.0 L of 0.010 M ${\text{SO}4}_{}{}^{\text{2−}}?$

Assuming that no equilibria other than dissolution are involved, calculate the concentrations of ions in a saturated solution of each of the following (see Appendix J for solubility products).

(a) TlCl

(b) BaF ₂

(c) Ag ₂ CrO ₄

(d) CaC ₂ O ₄ ·H ₂ O

(e) the mineral anglesite, PbSO ₄

Assuming that no equilibria other than dissolution are involved, calculate the concentrations of ions in a saturated solution of each of the following (see Appendix J for solubility products):

(a) AgI

(b) Ag ₂ SO ₄

(c) Mn(OH) ₂

(d) Sr(OH) ₂ ·8H ₂ O

(e) the mineral brucite, Mg(OH) ₂

The following concentrations are found in mixtures of ions in equilibrium with slightly soluble solids. From the concentrations given, calculate K _sp for each of the slightly soluble solids indicated:

(a) AgBr: [Ag ⁺ ] = 5.7 $\times$ 10 ^–7 M , [Br ^– ] = 5.7 $\times$ 10 ^–7 M

(b) CaCO ₃ : [Ca ²⁺ ] = 5.3 $\times$ 10 ^–3 M , $[{\text{CO}}_3{}^{\text{2−}}]$ = 9.0 $\times$ 10 ^–7 M

(c) PbF ₂ : [Pb ²⁺ ] = 2.1 $\times$ 10 ^–3 M , [F ^– ] = 4.2 $\times$ 10 ^–3 M

(d) Ag ₂ CrO ₄ : [Ag ⁺ ] = 5.3 $\times$ 10 ^–5 M , 3.2 $\times$ 10 ^–3 M

(e) InF ₃ : [In ³⁺ ] = 2.3 $\times$ 10 ^–3 M , [F ^– ] = 7.0 $\times$ 10 ^–3 M

The following concentrations are found in mixtures of ions in equilibrium with slightly soluble solids. From the concentrations given, calculate K _sp for each of the slightly soluble solids indicated:

(a) TlCl: [Tl ⁺ ] = 1.21 $\times$ 10 ^–2 M , [Cl ^– ] = 1.2 $\times$ 10 ^–2 M

(b) Ce(IO ₃ ) ₄ : [Ce ⁴⁺ ] = 1.8 $\times$ 10 ^–4 M , $[{\text{IO}}_3{}^{\text{−}}]$ = 2.6 $\times$ 10 ^–13 M

(c) Gd ₂ (SO ₄ ) ₃ : [Gd ³⁺ ] = 0.132 M , $[{\text{SO}}_{\text{4}}{}^{\text{2−}}]$ = 0.198 M

(d) Ag ₂ SO ₄ : [Ag ⁺ ] = 2.40 $\times$ 10 ^–2 M , $[{\text{SO}}_{\text{4}}{}^{\text{2−}}]$ = 2.05 $\times$ 10 ^–2 M

(e) BaSO ₄ : [Ba ²⁺ ] = 0.500 M , $[{\text{SO}}_{\text{4}}{}^{\text{2−}}]$ = 2.16 $\times$ 10 ^–10 M

Which of the following compounds precipitates from a solution that has the concentrations indicated? (See Appendix J for K _sp values.)

(a) KClO ₄ : [K ⁺ ] = 0.01 M , $[{\text{ClO}}_4{}^{\text{−}}]$ = 0.01 M

(b) K ₂ PtCl ₆ : [K ⁺ ] = 0.01 M , $[{\text{PtCl}}_{\text{6}}{}^{\text{2−}}]$ = 0.01 M

(c) PbI ₂ : [Pb ²⁺ ] = 0.003 M , [I ^– ] = 1.3 $\times$ 10 ^–3 M

(d) Ag ₂ S: [Ag ⁺ ] = 1 $\times$ 10 ^–10 M , [S ^2– ] = 1 $\times$ 10 ^–13 M

Which of the following compounds precipitates from a solution that has the concentrations indicated? (See Appendix J for K _sp values.)

(a) CaCO ₃ : [Ca ²⁺ ] = 0.003 M , $[{\text{CO}}_{\text{3}}{}^{\text{2−}}]$ = 0.003 M

(b) Co(OH) ₂ : [Co ²⁺ ] = 0.01 M , [OH ^– ] = 1 $\times$ 10 ^–7 M

(c) CaHPO ₄ : [Ca ²⁺ ] = 0.01 M , $[{\text{HPO}}_{\text{4}}{}^{\text{2−}}]$ = 2 $\times$ 10 ^–6 M

(d) Pb ₃ (PO ₄ ) ₂ : [Pb ²⁺ ] = 0.01 M , $[{\text{PO}}_{\text{4}}{}^{\text{3−}}]$ = 1 $\times$ 10 ^–13 M

Calculate the concentration of Tl ⁺ when TlCl just begins to precipitate from a solution that is 0.0250 M in Cl ^– .

Calculate the concentration of sulfate ion when BaSO ₄ just begins to precipitate from a solution that is 0.0758 M in Ba ²⁺ .