pH Calculatorとは？
pH measures how acidic or basic an aqueous solution is. This calculator converts between pH, pOH, hydrogen ion concentration [H⁺], and hydroxide ion concentration [OH⁻] using the relations pH = −log₁₀[H⁺] and pH + pOH = 14 at 25 °C. Enter a known ion concentration, pH, pOH, or the molarity of a strong monoprotic acid or monohydroxy base (e.g. HCl, NaOH) and get all related values instantly. Supports M, mM, µM, and nM. Runs in your browser with no signup.
pH Calculatorの使い方
- Choose a mode: [H⁺] → pH, [OH⁻] → pH, pH → ions, pOH → pH, strong acid, or strong base.
- Enter the known value (scientific notation like 1e-7 is supported for concentrations).
- Select a concentration unit when the mode uses molarity or ion concentration.
- Read pH, pOH, [H⁺], and [OH⁻] in the results panel.
- Copy the summary for lab notes or homework.
よくある使用例
- Finding pH of 0.1 M HCl or 0.01 M NaOH in introductory chemistry
- Converting [H⁺] = 1×10⁻⁷ M (pure water) to pH 7
- Checking pH and [OH⁻] after entering a measured pOH value
よくある質問
- How is pH calculated?
- pH = −log₁₀[H⁺], where [H⁺] is the hydrogen ion concentration in mol/L. A lower pH means a more acidic solution.
- What is the relationship between pH and pOH?
- At 25 °C, pH + pOH = 14 (pKw = 14). Knowing one lets you calculate the other and both ion concentrations.
- How do I find pH of a strong acid?
- For a strong monoprotic acid like HCl or HNO₃, [H⁺] equals the acid molarity. Enter that concentration in the Strong acid mode.
- Does this work for weak acids?
- No — weak acids only partially dissociate. Use Ka and an ICE table, or a dedicated weak-acid calculator, for accurate pH.
