免费缓冲液pH计算器
使用Henderson-Hasselbalch方程计算缓冲液pH。
Buffer pH
4.76
Buffer pH vs pKa of Weak Acid
公式
## Henderson-Hasselbalch Equation ### Formula **pH = pKa + log₁₀([A⁻] / [HA])** Where: - **pH** = hydrogen ion activity - **pKa** = acid dissociation constant (log scale) - **[A⁻]** = concentration of conjugate base - **[HA]** = concentration of weak acid When [A⁻] = [HA], pH = pKa. Buffers resist pH changes best within ±1 of the pKa.
计算示例
An acetate buffer with pKa = 4.76, [CH₃COO⁻] = 0.1 M, [CH₃COOH] = 0.1 M.
- 01pH = pKa + log₁₀([A⁻]/[HA])
- 02pH = 4.76 + log₁₀(0.1/0.1)
- 03pH = 4.76 + log₁₀(1)
- 04pH = 4.76 + 0
- 05pH = 4.76
常见问题
What is the Henderson-Hasselbalch equation?
It relates the pH of a buffer solution to the pKa of the acid and the ratio of conjugate base to acid concentrations. It is derived from the Ka expression by taking logarithms.
When is this equation most accurate?
It works best when the buffer ratio [A⁻]/[HA] is between 0.1 and 10, i.e., within ±1 pH unit of the pKa.
Can I use this for basic buffers?
Yes. Use pKa of the conjugate acid, [A⁻] as the base form, and [HA] as the acid form of the buffer pair.
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