Resistance Thermometer
Definition and meaning of Resistance Thermometer in chemistry.
A resistance thermometer is a temperature measurement device that determines temperature by measuring the electrical resistance of a metal conductor (typically platinum) that changes predictably with temperature.
In more detail
As temperature increases or decreases, the electrical resistance of certain metals like platinum changes in a highly reproducible, well-characterized manner (nearly linear over much of the usable range, though precisely described by the Callendar-Van Dusen equation). A resistance thermometer exploits this physical principle by measuring the resistance change and converting it into a temperature reading using calibrated electronics. Platinum resistance thermometers (PRTs), also called resistance temperature detectors (RTDs), are highly valued in chemistry labs because they offer superior accuracy, excellent repeatability, and a wide usable temperature range. They represent a significant improvement over traditional liquid-in-glass thermometers for demanding experimental work requiring precise temperature control.
Key facts
| Field | Analytical Chemistry |
|---|---|
| Common material | Platinum (Pt) |
| Typical temperature range | -200°C to +850°C |
| Typical accuracy | ±0.1°C to ±1°C depending on quality |
A chemistry lab measuring enzyme reaction kinetics in a precisely controlled water bath might use a platinum resistance thermometer to confirm the bath temperature is exactly 37.0°C, as this precision is essential for obtaining reproducible kinetic measurements.
Frequently asked questions
How does a resistance thermometer work?
It measures the change in electrical resistance of a metal (usually platinum) as temperature changes; the resistance is converted electronically to a temperature reading using a calibrated scale.
Why is platinum preferred for resistance thermometers?
Platinum has a highly predictable, well-characterized resistance-temperature relationship, excellent chemical stability, low hysteresis, and a very wide usable temperature range.