Chemistry ?

7.
CaSO₄(s) ⇌ Ca²⁺(aq) + SO₄²⁻(aq)  Ksp = ?
Initial:              0 M           0 M
Change:         +s M        +s M
Eqm:    　　    s M           s M

At equilibrium:
Ksp = [Mg²⁺][SO₄²⁻] = s² = (7.02 × 10⁻³)² = 4.93 × 10⁻⁵

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8.
Zn(OH)₂(s) ⇌ Zn²⁺(aq) + 2OH⁻(aq)  Ksp = ?
Initial:                 0 M          0 M
Change:           +s M        +2s M
Eqm:    　　　   s M          2s M

At equilibrium:
Ksp = [Zn²⁺][OH⁻]² = (s)(2s)² = 4s³ = 4 × (1.01 × 10⁻⁴)³ = 4.12 × 10⁻¹²

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9.
Bi(OH)₃(s) ⇌ Bi³⁺(aq) + 3OH⁻(aq)  Ksp = ?
Initial:              0 M           0 M
Change:         +s M        +3s M
Eqm:        　   s M           3s M

At equilibrium:
Ksp = [Bi³⁺][OH⁻]³ = (s)(3s)³ = 27s⁴ = 27 × (1.4 × 10⁻⁴)⁴ = 1.04 × 10⁻¹⁴

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10.
AgBr(s) ⇌ Ag⁺(aq) + Br⁻(aq)   Ksp = 5.35 × 10⁻¹³

Initial:          0 M          0 M

Change:    +s M         +s M
Eqm:           s M           s M

At equilibrium:
Ksp = [Ag⁺][Br⁻]
s² = 5.35 × 10⁻¹³
Solubility of AgBr, s = √(5.35 × 10⁻¹³) mol L⁻¹ = 7.31 × 10⁻⁷ mol L⁻¹

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11.
Molar mass of AgBr = (107.9 + 79.9) g/mol = 187.8 g/mol
Solubility of AgBr = (7.31 × 10⁻⁷ mol/L⁻¹) × (187.8 g/mol) = 1.37 × 10⁻⁴ g L⁻¹