What is temperature?

• A measure of the hotness or coldness of a substance

• The average kinetic energy per molecule in a substance

Three Scales

• Fahrenheit

• Celsius

• Kelvin

Daniel Fahrenheit (1686-1736)

• First used alcohol (1709)

• Mercury much more accurate (1714)

• Used four temperature points (1724)

– Salt-ice mixture (0)

– Freezing point of water (30)

– Body (90)

– Boiling point of water (240)

• Adjusted his temperatures

Fahrenheit Scale

• Freezing point of water 32˚F

• Boiling point of water 212˚F

• Body 98.6˚F

Anders Celsius (1701-1744)

• Used just two points for his scale (1742)

– Freezing point of water

– Boiling point of water

• Performed numerous experiments to see if the freezing point and the boiling point were consistent with latitude

Celsius Scale

• Freezing point of water 0˚C

• Boiling point of water 100˚C

Lord Kelvin (1824-1907)

• Coldest temperature possible (1748)

–Absolute Zero

•0 K

•273˚C

Conversions

Convert 40

Convert 240K

Conversions

Convert 30

Conversions

Convert 75˚F to