A solution is 0.10 M in Ca(NO3)2. What would the concentration of NaOH need to be for a precipitate of Ca(OH)2 to form?
回答 (1)
2016-04-17 6:04 pm
In aqueous solution , Ca(NO₃)₂ completely dissociates to give Ca²⁺ and NO₃⁻ ions, i.e.
[Ca²⁺] = [Ca(NO₃)₂]ₒ = 0.10 M
Ca(OH)(s) ⇌ Ca²⁺(aq) + 2OH⁻(aq) ... Ksp = 5.5 × 10⁻⁶
When the precipitate of Ca(OH)₂ is just formed :
Ksp = [Ca²⁺][OH⁻]²
5.5 × 10⁻⁶ = 0.10 × [OH⁻]²
[OH⁻] =√(5.5 × 10⁻⁶ / 0.10) M
[OH⁻] = 7.4 × 10⁻³ M
[NaOH] need = [OH⁻] = 7.4 × 10⁻³ M
[Ca²⁺] = [Ca(NO₃)₂]ₒ = 0.10 M
Ca(OH)(s) ⇌ Ca²⁺(aq) + 2OH⁻(aq) ... Ksp = 5.5 × 10⁻⁶
When the precipitate of Ca(OH)₂ is just formed :
Ksp = [Ca²⁺][OH⁻]²
5.5 × 10⁻⁶ = 0.10 × [OH⁻]²
[OH⁻] =√(5.5 × 10⁻⁶ / 0.10) M
[OH⁻] = 7.4 × 10⁻³ M
[NaOH] need = [OH⁻] = 7.4 × 10⁻³ M
收錄日期: 2021-04-18 14:45:03
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