Which instrument is used to determine the acidity or alkalinity of a soil or water solution?

Which instrument is used to determine the acidity or alkalinity of a soil or water solution?

• A. Graduated Cylinder
• B. Calipers
• C. pH Meter
• D. Spectrophotometer

Answer: (C)

Measuring acidity or alkalinity centers on pH, which reflects hydrogen ion activity in a solution. A pH meter provides a direct, numeric readout of pH by using a glass electrode and a reference electrode to detect this activity and convert it into a value usually between 0 and 14. It’s the most precise and practical tool for determining soil or water pH, and readings are reliable once the instrument is properly calibrated with standard buffer solutions. In practice, you calibrate the meter, rinse the probe, immerse it in the sample, and wait for the reading to stabilize. The other devices serve different purposes: a graduated cylinder measures volume, not acidity; calipers measure dimensions; a spectrophotometer assesses how much light a sample absorbs at specific wavelengths to determine concentration, which doesn’t directly measure pH.

Measuring acidity or alkalinity centers on pH, which reflects hydrogen ion activity in a solution. A pH meter provides a direct, numeric readout of pH by using a glass electrode and a reference electrode to detect this activity and convert it into a value usually between 0 and 14. It’s the most precise and practical tool for determining soil or water pH, and readings are reliable once the instrument is properly calibrated with standard buffer solutions. In practice, you calibrate the meter, rinse the probe, immerse it in the sample, and wait for the reading to stabilize.

The other devices serve different purposes: a graduated cylinder measures volume, not acidity; calipers measure dimensions; a spectrophotometer assesses how much light a sample absorbs at specific wavelengths to determine concentration, which doesn’t directly measure pH.