What is the purpose of using buffer solutions in pH meter calibration?

• A. To Standardize the Ionic Strength of All Solutions
• B. To Provide Known pH Values at Different Temperatures
• C. To Dry the pH Probe Between Measurements
• D. To Calibrate the Spectrophotometer's Absorbance Scale

Answer: (B)

Calibration of a pH meter relies on using buffer solutions that have precisely known pH values at a specific temperature. By immersing the electrode in these buffers, the meter can be adjusted so its reading matches the true pH of those references, establishing the correct offset and slope for the entire scale. Because the pH of buffers shifts with temperature, calibrating at the temperature in which you’ll measure samples (or using temperature-compensated buffers) keeps readings accurate. These buffers aren’t about standardizing ionic strength across all solutions, drying the probe, or calibrating a spectrophotometer—those tasks involve different techniques or instruments.