Temperature
Temperature is a qualitative measurement- movement
of molecules
How hot or cold something is.
Fahrenheit
Celsius
oF = 9/5C + 32
oC = 5/9 (F-32)
also
equal to
1.8
Note the similarities in the equations. The relationship between boiling
points and freezing points on each scale must be accounted for in the
conversion formulas.
Hint: I use 1.8 in the formulas for all conversions because I can change
the 9/5 fraction to a decimal number which is easier to use and think
about in calculations. oF = 1.8C + 32 or oC = (F-32)/1.8
Comparison of Scales
A)
The difference between the freezing point and boiling point of
water is different in each of the scales:
On the Fahrenheit scale Boiling Point of water is 212oF and the
Freezing Point is 32oF. The difference between the points is
180oF.
On the centigrade scale, Celsius, Boiling Point of water is100oC and
the Freezing Point is 0oC. The difference between the points is
100oC.
The ratio between scales is thus 180/100 = 5/9 or 1.8 Fahrenheit
units/ 1 Celsius unit.
Another way to say it:
A 10oC change is equal to 18oF
This factor must be accounted for when doing a conversion between
scales
Comparison of Scales
B)
We also need to make a correction for the
fact that the corresponding freezing points
are not numerically equal:
0oC and 32oF
Subtract 32 if going from Fahrenheit to
Celsius
2) Add 32 if going from Celsius to Fahrenheit
1)
Kelvin Scale
 We do need to mention the Kelvin scale. Sometimes chemists,
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most often physicists and engineers use Kelvin for temperature
calculations.
Kelvin is the degree unit, no degree symbol is used.
The coldest possible temperature is -273oC and is considered
to be absolute zero, as such it is given the value 0 on the
Kelvin scale.
1K = 1oC because the difference between the boiling (373) and
freezing (273) points in K is 100 units. This is the same
difference on the Celsius scale.
To calculate Kelvin use the following formula which accounts
for the absolute zero value:
K = oC + 273