幫我證明這個化學公式

2010-06-23 8:25 pm
CH3COO-+H2O<->CH3COOH+OH

Kb=[CH3COOH][OH-]/[CH3COO-]

[H+][OH-]=10^-14 PH+POH=14

Ka*Kb=10^-14 PKa+Pkb=14

如何證明成 PH=PKa-log[CH3COO-]/[CH3COOH]

回答 (3)

2010-06-24 1:39 pm
✔ 最佳答案
應是:pH = pKa - log([CH3­COOH]/[CH3COO⁻])
或者:pH = pKa + log([CH3­COO⁻]/[CH3COOH])


證明:
CH­3­COO⁻ + H2O ⇌ CH3COOH + OH⁻ (Kb)
Kb = [CH3COOH][OH⁻]/[CH3COO⁻]

KaKb = 10⁻¹⁴
KaKb = [H⁺][OH⁻]
Ka = [H⁺][OH⁻] x (1/Kb)
Ka = [H⁺][OH⁻] x [CH3COO⁻]/[CH3COOH][OH⁻]
Ka = [H⁺][CH3COO⁻]/[CH3COOH]
log(Ka) = log([H⁺][CH3COO⁻]/[CH3COOH])
log(Ka) = log[H⁺] + log([CH3COO⁻]/[CH3COOH])
log(Ka) = log[H⁺] + log([CH3COO⁻]/[CH3COOH])
-log[H⁺] = -log(Ka) + log([CH3COO⁻]/[CH3COOH])

pH = -log[H⁺] 及 p(Ka) = -log(Ka)
pH = pKa + log([CH3COO⁻]/[CH3COOH])

pH = pKa + log([CH3COOH]/[CH3COO⁻])⁻¹
pH = pKa - log([CH3COOH]/[CH3COO⁻])
參考: andrew
2010-06-24 1:17 am
同學,這應該是妳化學期末考的加分題吧

加分題有跟沒有都一樣拉

沒能力就不要加嘛...

可是俗話說...〝不齒下問〞

妳也沒錯拉

1/2離你不遠了

說錯...○培是2/3
參考: 陳X慧指導
2010-06-23 8:37 pm
您的證明從HA-->H+ + A- 就可以證明出來


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