Thermometry pchem lec

Thermometry: measuring temperature.

Q1: What is temperature? Just a number?

A1 - the degree or intensity of heat present in a substance.

A2 - a measurement of the average kinetic energy of a particle in a system; 3/2kT <--per molecule

Q2: How do we measure temperature?

A1 - Most commonly we use a thermometer.

Temperature is never measured!

We measure other system variable and then relate this back to temperature/average kinetic energy of the particles.

- Most common is change in volume as a function of changes in temperature

- changes is voltage as a function of changed in temperature (thermocouple, used for measuring very hot environments, like kilns or flames.

- changes is color as a function of changed in temperature (thermochromic)

- changes is pressure as a function of changed in temperature (used to develop the idea of an absolute zero, zero pressure zero temperature.)

- IR light emission (intensity/wavelength) as a function of temperature, IR thermometer.