A pH meter is an instrument used to measure the acidity or alkalinity of a solution by determining its pH. Here’s a explanation of how it works:
1. Components of a pH Meter
- Glass electrode (sensing electrode) – Sensitive to hydrogen ion (H⁺) concentration in the solution.
- Reference electrode – Maintains a constant potential and completes the electrical circuit.
- Voltmeter or electronic meter – Measures the voltage difference between the electrodes and converts it to pH.
2. Working Principle
- The glass electrode develops a voltage that depends on the H⁺ concentration in the solution.
- The reference electrode has a stable voltage.
- The meter measures the potential difference between the electrodes.
- This potential difference is related to pH using the Nernst equation: the higher the H⁺ concentration, the lower the pH, and vice versa.
- The meter converts this voltage into a pH reading displayed on the screen.
3. Steps to Measure pH
- Calibrate the pH meter using standard buffer solutions (usually pH 4, 7, and 10).
- Rinse the electrodes with distilled water.
- Immerse the electrodes into the solution to be tested.
- Wait until the reading stabilizes and note the pH.
4. Applications
- Testing water quality
- Monitoring soil acidity in agriculture
- Controlling pH in chemical and pharmaceutical processes
- Food and beverage testing
In simple words: A pH meter measures how acidic or basic a solution is by detecting how many hydrogen ions are present and converting that into a pH value.