Temperature scales

The Fahrenheit and Celsius scales are commonly used to measure temperature. Both are based on the properties of water. The Celsius scale defines zero degrees as the freezing point of water and 100 degrees as the boiling point of water. The Fahrenheit scale defines 32 degrees as the freezing point of water and 212 degrees as the boiling point of water. Read the text aloud
Celsius and Fahrenheit are relative temperature scalesThe Fahrenheit scale has 180 degrees between the boiling and freezing points of water. The Celsius scale, however, has 100 degrees between the same two points. Therefore, a change of 180°F is equivalent to a change of 100°C. To convert from degrees Celsius to degrees Fahrenheit, you multiply by a factor of 9/5 then add 32°, because 0ºC is the same as 32ºF. Equations (23.1) and (23.2) are used to convert temperatures between the two scales. Read the text aloud Show Deriving one equation from the other
(23.1) T C = 5 9 ( T F 32 )
TC  = temperature in degrees Celsius (°C)
TF  = temperature in degrees Fahrenheit (°F)
Celsius
temperature scale

(23.2) T F = 9 5 T C +32
TF  = temperature in degrees Fahrenheit (°F)
TC  = temperature in degrees Celsius (°C)
Fahrenheit
temperature scale
The choice of 0ºC as the freezing point of water is quite arbitrary in that water molecules do not have zero kinetic energy at 0ºC. Instead, the kinetic energy in molecular motion is effectively zero at a much lower temperature called absolute zero. Absolute zero is −273.15ºC (−459.7°F) and is the minimum possible temperature that matter can have. Temperature cannot go lower than absolute zero. Read the text aloud Show Temperatures below absolute zero?
The Kelvin temperature scale is an absolute temperature scale
The Kelvin scale of temperature starts at absolute zero. There are no “degrees” in the Kelvin scale, even though 1 K represents the same temperature difference as 1ºC. Since temperatures in kelvins are referenced to absolute zero, a temperature on the Kelvin scale is called an absolute temperature. Most equations relating to heat, such as the gas laws, use absolute temperatures in kelvins. You can convert between degrees Celsius and kelvins by using equation (23.3). Read the text aloud
(23.3) T K = T C +273.15
TK  = temperature in kelvins (K)
TC  = temperature in degrees Celsius (°C)
Kelvin
temperature scale
Which temperature is hotter, 200°F or 95°C? Show

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