TC pipets are calibrated with which substance?

• A. Mercury
• B. Distilled water
• C. Ethanol
• D. Olive oil

Answer: (A)

Calibrating TC pipettes relies on a liquid with a precisely known density so that the delivered volume can be determined from the measured mass. Distilled water is the standard calibrant because its density is well established at the calibration temperature, and it matches the liquid you’ll typically dispense in routine work. The usual method is gravimetric: weigh a receiving vessel, dispense the nominal volume, weigh again, and convert the mass of water to volume using water’s density at the calibration temperature. Mercury isn’t used due to its toxicity and contamination risk, and ethanol or olive oil have densities and temperature dependencies that introduce greater uncertainty. So, distilled water is the best and most practical choice for calibrating pipettes.