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A 0.83 M solution of a weak acid HA is 2.40 % ionized. What are the H+, A, and HA concentrations at equilibrium? What is Ka?
What are the H+, A, and HA concentrations?
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2018-01-17 6:32 am
✔ 最佳答案
Concentrations for a weak acid.....HA <==> H+ ....+.... A-............. Ka = ???
0.83M......0 .............0
0.81M.....0.020M....0.020M ..... equilibrium concentrations
Ka = [H+][A-] / [HA]
Ka = (0.020)² / 0.81
Ka = 4.9x10^-4
2018-01-17 6:28 am
HA(aq) ⇌ H⁺(aq) + A⁻(aq) …… Ka
Ionization of each mole of HA gives 2.40% mole of H⁺ ions and 2.40% mole of A⁻ ions.
At equilibrium :
[H⁺] = (0.83 M) × 2.40% = 0.020 M
[A⁻] = (0.83 M) × 2.40% = 0.020 M
[HA] = (0.83 M) × (100% - 2.4%) = 0.81 M
Ka = [H⁺] [A⁻] / [HA] = 0.020² / 0.81 = 4.9 × 10⁻⁴
Ionization of each mole of HA gives 2.40% mole of H⁺ ions and 2.40% mole of A⁻ ions.
At equilibrium :
[H⁺] = (0.83 M) × 2.40% = 0.020 M
[A⁻] = (0.83 M) × 2.40% = 0.020 M
[HA] = (0.83 M) × (100% - 2.4%) = 0.81 M
Ka = [H⁺] [A⁻] / [HA] = 0.020² / 0.81 = 4.9 × 10⁻⁴
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https://hk.answers.yahoo.com/question/index?qid=20180116220303AAECxeT