Chapter 16 Heat and Temperature

Temperature is a measure of how hot (or cold) something is compared to a reference point

Specifically, temperature is a measure of the average kinetic energy of the particles in an object due to their motions through space

Thermal Energy Depends on the mass, temperature and phase (solid, liquid, gas) of an object

Thermal contraction Slower particles collide less often and exert less force

Thermal expansion Occurs when particles of matter move farther apart as temperature increases-gases expand more than liquids and liquids expand more than solids

Thermal expansion is based on the attraction among the particles in the substance Glass thermometers are based on this principle As the temperature rises, the alcohol expands

Thermometer Anything that changes in a measurable & predictable way when temperature changes

Temperatures can be expressed using different scales, for example: Fahrenheit Celsius Kelvin The same temperature has different readings on each scales.

Different temperature scales are used for different purposes Fahrenheit is used in the US for meteorology and in medicine Celsius is used in science & for non-science in the rest of the world Kelvin is used in physics, chemistry & astronomy

Absolute zero – the coldest possible temperature molecular energy is at a minimum when the volume of an ideal gas becomes zero -273.16C

Heat is energy transfer between objects that are different temperatures Energy is always transferred from higher-temperature objects to lower- temperature objects until both objects are at the same temperature