Pycnometers are calibrated by filling them with water at what temperature to the calibration line and determining the mass?

• A. Pycnometers are calibrated by filling them with water at 30 ± 2 °C to the calibration line.
• B. Pycnometers are calibrated by filling them with water at 40 ± 2 °C to the calibration line.
• C. Pycnometers are calibrated by filling them with water at 23 ± 1.7 °C (73.4 ± 3 °F) to the calibration line and determining the mass.
• D. Pycnometers are calibrated by filling them with water at 10 ± 1 °C to the calibration line.

Answer: (C)

When you calibrate a pycnometer, you rely on the known density of water at a specific temperature. The pycnometer has a fixed internal volume, so filling it to the calibration line with water and weighing gives you a mass that corresponds to that water density. Using a standard temperature where water density is well established—23°C (about 73.4°F) with a small allowable variation—lets you convert that mass into an accurate volume and ensures consistent density measurements later. The tolerance accounts for minor room-temperature differences without changing the reference density. Using other temperatures would mean different water densities and would require different reference data, leading to less consistent results.