How do you calibrate a thermometer using the ice-water method?

• A. Place the thermometer in a mixture of ice and water at 32°F (0°C) until stabilized.
• B. Submerge the thermometer in ice at 32°F with no water until stabilized.
• C. Place the thermometer in a mixture of ice and water at 32°F (0°C) until stabilized and adjust as necessary.
• D. Use room temperature as a reference.

Answer: (C)

Calibrating with the ice-water method uses a known, fixed temperature: 0°C (32°F). To do this, make a slurry of crushed ice and clean water and immerse the thermometer so the sensing portion is in the mixture. Allow it to stabilize so the reading reflects the 0°C point, then adjust the thermometer as needed until it reads exactly 0°C (32°F). This ensures subsequent measurements are accurate. Using ice with no water won’t provide a reliable, stable 0°C reading, and room-temperature references don’t give a fixed calibration point.