Adding kinetic energy to the molecules of a liquid makes them move farther apart. Temperature is measured by measuring how much a liquid expands inside a thermometer. Older thermometers used mercury, a gray liquid metal. Mercury is toxic, so newer thermometers use colored alcohol instead.
Temperature scales:
|
What Happens |
Celsius |
Kelvin |
Fahrenheit |
|
Water boils |
100 |
373 |
212 |
|
“Room Temperature” |
25 |
298 |
77 |
|
Water freezes |
0 |
273 |
32 |
|
Absolute Zero |
−273 |
0 |
−460 |
absolute zero: the temperature at which it an object cannot transfer any more heat to another object. It is not possible to reach absolute zero, though scientists have come close.
Many people (including the authors of our textbook, and very likely the people who will be writing the chemistry MCAS test) mistakenly think that molecules stop moving at absolute zero.
Celsius (°C): the most common scale worldwide for measuring temperature. Water boils at 100°C and freezes at 0°C.
Kelvin (K): the temperature scale used in equations that involve temperature. This is because most equations wouldn’t make sense unless a temperature of zero really meant the lowest possible temperature.
Because 0°C = 273 K, you can get the Kelvin temperature by just adding 273.
Example conversions:
If the temperature is 15°C outside, in Kelvin it would be 15 + 273 = 288 K.
If a gas has a temperature of 350 K, this would be 350 − 273 = 77°C.