Thermometer, Precision

Quick Answer: The Thermometer, Precision is a liquid-in-glass laboratory thermometer intended for readings finer than an ordinary lab thermometer allows, typically by covering a narrower range with closer graduations. A precision thermometer is used where small temperature differences decide the result, such as calorimetry, melting-point work and controlled water baths.

Where Fractions of a Degree Matter

In a calorimetry experiment the whole temperature rise may be only a few degrees, so reading to the nearest whole degree leaves a large percentage error. A precision thermometer spreads a shorter span over the same length of stem, so each degree takes up more space and can be subdivided. That is why such thermometers are often sold in sets that together cover a wide range, each one covering a narrow band.

Using one well takes patience. Stir the liquid steadily, allow the thread to settle before each reading, and use a magnifier held square to the stem so parallax does not undo the finer scale. Tap the stem lightly before reading a slowly rising thread, which can stick in a fine bore. In calorimetry, record readings at fixed time intervals, then extrapolate the cooling curve back to the moment of mixing to find the true maximum.

For melting points the thermometer is paired with a melting point tube or a heating block; for enthalpy experiments, with a calorimeter. The range, subdivision and immersion depth of this item are not given in the title, and they decide which of these jobs it suits.

Specifications

Applications

• Calorimetry experiments on enthalpy of neutralisation, solution or combustion
• Melting-point determination of organic solids in a heating bath
• Checking the set point of thermostatic water baths and incubators
• Specific heat capacity experiments in college physics

Care & Handling

• Reserve it for work that needs it; using it as an everyday bench thermometer shortens its life.
• Never let the liquid rise beyond the top graduation; a narrow-range thermometer is easily over-ranged by a bath that overshoots.
• Rejoin any separated thread before use, and re-test at a known point afterwards.
• Keep it upright in a padded case away from vibration.

Why Choose LabEquip

College chemistry and physics departments buy these thermometers for calorimetry and physical-chemistry practicals, often a few per lab rather than one per bench. LabEquip lists them in General Lab Products; tell us the span you need to cover on the contact page.

Frequently Asked Questions

How is a precision thermometer different from an ordinary one?

It is designed to be read more finely, usually by covering a narrower span with closer graduations. It needs more careful use, and because each one covers less range, several may be needed to cover the same span.

Why does the thread sometimes jump instead of rising smoothly?

In a fine bore the liquid can stick briefly and then move in steps. A light tap on the stem before reading helps the thread settle at its true position.

Do I need a magnifier?

It helps. Fine graduations are easy to misread by half a division, and a small magnifier held square to the stem at thread level reduces that error.

How do I find the true maximum in calorimetry?

Record the temperature at regular intervals before, during and after mixing, plot the readings against time, and extrapolate the cooling part of the curve back to the time of mixing. This corrects for heat lost while the temperature was rising.

Can it be used in an oil bath for melting points?

Yes, if the range covers the expected melting point with margin and the stem is immersed to its stated depth. Heat slowly near the melting point so the thermometer keeps pace with the sample.

Does it need a separate calibration?

For teaching work an ice-point check is usually sufficient. For research or quality-control work, labs often have precision thermometers compared against a reference by a calibration laboratory.

Last Updated: September 2026