This tool calculates the pH and pOH of aqueous solutions for strong and weak acids, strong and weak bases, as well as acidic and basic buffer systems at 25°C.
Users select the solution type, enter the concentration, pKa (when required), and buffer ratio (for buffers). The tool instantly provides the exact pH, pOH, [H⁺], and [OH⁻] values along with the underlying calculation method.
The calculations use the following equations:
Strong acids:
\[ \text{pH} = -\log C \]
Strong bases:
\[ \text{pOH} = -\log C \quad \Rightarrow \quad \text{pH} = 14 - \text{pOH} \]
Weak acids (with quadratic solution when approximation is insufficient):
\[ [\ce{H+}] \approx \sqrt{K_a \cdot C} \]
Exact: solution of \( K_a = \frac{[\ce{H+}][\ce{A-}]}{[\ce{HA}]} \)
Weak bases (via conjugate acid pKa):
\[ K_b = \frac{K_w}{K_a} \quad , \quad [\ce{OH-}] \approx \sqrt{K_b \cdot C} \]
Acidic buffers (HA + A⁻):
\[ \text{pH} = \text{p}K_a + \log\left(\frac{[\ce{A-}]}{[\ce{HA}]}\right) \]
Basic buffers (B + BH⁺):
\[ \text{pH} = \text{p}K_a + \log\left(\frac{[\ce{B}]}{[\ce{BH+}]}\right) \]
where \( K_w = 1.0 \times 10^{-14} \) at 25°C.
The tool also displays a pH gauge and titration curves to visualize behavior during acid-base titrations.
Ideal for predicting solution acidity, designing buffers, planning titrations, and educational use in general, analytical, and pharmaceutical chemistry.
