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The Ksp of Cobalt (II) hydroxide is 2.5E-18. By externally changing the pH, it will change the concentration of cobalt (II) in solution. What is the needed pH of a saturated solution of cobalt (II) hydroxide in order to have a concentration of cobalt equal to 1.0E-9. Give your answer with at least one decimal point.
The Ksp of Cobalt (II) hydroxide is 2.5E-18. By externally changing the pH, ?
2020-04-12 3:19 pm
回答 (1)
2020-04-12 3:29 pm
Co(OH)₂(s) ⇌ Co²⁺(aq) + 2OH⁻(aq) … Ksp = 2.5 × 10⁻¹⁸
In the saturated solution:
Ksp = [Co²⁺] [OH⁻]²
2.5 × 10⁻¹⁸ = (1.0 × 10⁻⁹) [OH⁻]²
[OH⁻] = √[(2.5 × 10⁻¹⁸)/(1.0 × 10⁻⁹)]
[OH⁻] = 5 × 10⁻⁵
pOH = -log[OH⁻] = -log(5 × 10⁻⁵) = 4.3
pH = pKw - pOH = 14.0 - 4.3 = 9.7
In the saturated solution:
Ksp = [Co²⁺] [OH⁻]²
2.5 × 10⁻¹⁸ = (1.0 × 10⁻⁹) [OH⁻]²
[OH⁻] = √[(2.5 × 10⁻¹⁸)/(1.0 × 10⁻⁹)]
[OH⁻] = 5 × 10⁻⁵
pOH = -log[OH⁻] = -log(5 × 10⁻⁵) = 4.3
pH = pKw - pOH = 14.0 - 4.3 = 9.7
收錄日期: 2021-04-24 07:47:23
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https://hk.answers.yahoo.com/question/index?qid=20200412071946AA2totJ