Для вычисления Кд и pH раствора CH3COOH воспользуемся следующими формулами:
Кд = CH3COO−CH3COO-CH3COO−H+H+H+ / CH3COOHCH3COOHCH3COOH
Уравнение сохранения массы для CH3COOH:C = CH3COOHCH3COOHCH3COOH + CH3COO−CH3COO-CH3COO−
Уравнение диссоциации:α = [CH3COO−]/[CH3COOH][CH3COO-] / [CH3COOH][CH3COO−]/[CH3COOH] * 100%
Из уравнения диссоциации можно выразить CH3COO−CH3COO-CH3COO− через CH3COOHCH3COOHCH3COOH:CH3COO−CH3COO-CH3COO− = α * CH3COOHCH3COOHCH3COOH
Также, из уравнения сохранения массы можно выразить CH3COO−CH3COO-CH3COO−:CH3COO−CH3COO-CH3COO− = C - CH3COOHCH3COOHCH3COOH
Подставив данные значения в уравнение диссоциации, получим:α = C−[CH3COOH]C - [CH3COOH]C−[CH3COOH] / CH3COOHCH3COOHCH3COOH 100%1.3 = C−[CH3COOH]C - [CH3COOH]C−[CH3COOH] / CH3COOHCH3COOHCH3COOH 100%1.3 * CH3COOHCH3COOHCH3COOH = C - CH3COOHCH3COOHCH3COOH
Из последнего уравнения можно выразить CH3COOHCH3COOHCH3COOH:1.3 * CH3COOHCH3COOHCH3COOH + CH3COOHCH3COOHCH3COOH = CCH3COOHCH3COOHCH3COOH = C / 2.3
Теперь можем вычислить CH3COO−CH3COO-CH3COO−:CH3COO−CH3COO-CH3COO− = α CH3COOHCH3COOHCH3COOH CH3COO−CH3COO-CH3COO− = 0.013 C/2.3C / 2.3C/2.3
Теперь можем подставить все значения в формулу Кд:Кд = [CH3COO−]<em>[H+][CH3COO-] <em> [H+][CH3COO−]<em>[H+] / CH3COOHCH3COOHCH3COOH Кд = 0.013</em>(C/2.3)<em>[H+]0.013 </em> (C / 2.3) <em> [H+]0.013</em>(C/2.3)<em>[H+] / C/2.3C / 2.3C/2.3 Кд = 0.013 H+H+H+
Теперь найдем pH по формуле:pH = -logH+H+H+ pH = -log0.013∗C/2.30.013 * C / 2.30.013∗C/2.3
Таким образом, мы можем вычислить Кд и pH для 0.1 г раствора CH3COOH при α = 1.3%.
Для вычисления Кд и pH раствора CH3COOH воспользуемся следующими формулами:
Константа диссоциации КдКдКд для уксусной кислоты CH3COOH:CH3COOH ⇌ CH3COO- + H+
Кд = CH3COO−CH3COO-CH3COO−H+H+H+ / CH3COOHCH3COOHCH3COOH
Уравнение сохранения массы для CH3COOH:
C = CH3COOHCH3COOHCH3COOH + CH3COO−CH3COO-CH3COO−
Уравнение диссоциации:
α = [CH3COO−]/[CH3COOH][CH3COO-] / [CH3COOH][CH3COO−]/[CH3COOH] * 100%
Из уравнения диссоциации можно выразить CH3COO−CH3COO-CH3COO− через CH3COOHCH3COOHCH3COOH:
CH3COO−CH3COO-CH3COO− = α * CH3COOHCH3COOHCH3COOH
Также, из уравнения сохранения массы можно выразить CH3COO−CH3COO-CH3COO−:
CH3COO−CH3COO-CH3COO− = C - CH3COOHCH3COOHCH3COOH
Подставив данные значения в уравнение диссоциации, получим:
α = C−[CH3COOH]C - [CH3COOH]C−[CH3COOH] / CH3COOHCH3COOHCH3COOH 100%
1.3 = C−[CH3COOH]C - [CH3COOH]C−[CH3COOH] / CH3COOHCH3COOHCH3COOH 100%
1.3 * CH3COOHCH3COOHCH3COOH = C - CH3COOHCH3COOHCH3COOH
Из последнего уравнения можно выразить CH3COOHCH3COOHCH3COOH:
1.3 * CH3COOHCH3COOHCH3COOH + CH3COOHCH3COOHCH3COOH = C
CH3COOHCH3COOHCH3COOH = C / 2.3
Теперь можем вычислить CH3COO−CH3COO-CH3COO−:
CH3COO−CH3COO-CH3COO− = α CH3COOHCH3COOHCH3COOH CH3COO−CH3COO-CH3COO− = 0.013 C/2.3C / 2.3C/2.3
Теперь можем подставить все значения в формулу Кд:
Кд = [CH3COO−]<em>[H+][CH3COO-] <em> [H+][CH3COO−]<em>[H+] / CH3COOHCH3COOHCH3COOH Кд = 0.013</em>(C/2.3)<em>[H+]0.013 </em> (C / 2.3) <em> [H+]0.013</em>(C/2.3)<em>[H+] / C/2.3C / 2.3C/2.3 Кд = 0.013 H+H+H+
Теперь найдем pH по формуле:
pH = -logH+H+H+ pH = -log0.013∗C/2.30.013 * C / 2.30.013∗C/2.3
Таким образом, мы можем вычислить Кд и pH для 0.1 г раствора CH3COOH при α = 1.3%.