How to Calculate pH of Strong Acids and Bases

pH Calculation Formulas:

\[ pH = -\log[H^+] \quad \text{(for acids)} \] \[ pOH = -\log[OH^-] \quad \text{(for bases)} \] \[ pH + pOH = 14 \]

Result:

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1. What is pH Calculation?

pH calculation determines the acidity or basicity of a solution using the concentration of hydrogen ions [H⁺] or hydroxide ions [OH⁻]. For strong acids and bases, which completely dissociate in water, the calculation is straightforward using logarithmic formulas.

2. How Does the Calculator Work?

The calculator uses the following formulas:

\[ pH = -\log[H^+] \quad \text{(for strong acids)} \] \[ pOH = -\log[OH^-] \quad \text{(for strong bases)} \] \[ pH + pOH = 14 \]

Where:

\( [H^+] \) — Hydrogen ion concentration (M)
\( [OH^-] \) — Hydroxide ion concentration (M)
\( pH \) — Measure of acidity (0-14)
\( pOH \) — Measure of basicity (0-14)

Explanation: For strong acids, pH is calculated directly from [H⁺] concentration. For strong bases, pOH is calculated from [OH⁻] concentration and then converted to pH using the relationship pH + pOH = 14.

3. Importance of pH Calculation

Details: Accurate pH calculation is essential in chemistry, biology, environmental science, and industrial processes. It helps determine solution properties, reaction rates, and biological compatibility.

4. Using the Calculator

Tips: Enter concentration in molarity (M), select whether it's a strong acid or strong base. The concentration must be greater than 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between strong and weak acids/bases?
A: Strong acids and bases completely dissociate in water, while weak ones only partially dissociate. This calculator is designed for strong acids and bases only.

Q2: What is the pH range?
A: pH ranges from 0 (very acidic) to 14 (very basic), with 7 being neutral. Strong acids typically have pH < 3, strong bases have pH > 11.

Q3: How accurate is this calculation for real solutions?
A: For dilute solutions of strong acids and bases, this calculation is very accurate. For concentrated solutions, activity coefficients may need to be considered.

Q4: Can this calculator be used for weak acids/bases?
A: No, weak acids and bases require different calculations involving acid dissociation constants (Ka or Kb) and equilibrium expressions.

Q5: What are some common strong acids and bases?
A: Common strong acids: HCl, H₂SO₄, HNO₃, HBr, HI. Common strong bases: NaOH, KOH, LiOH, Ca(OH)₂, Ba(OH)₂.