Temperature Scales
Mrs. Baldessari Chemistry
Section 5.7
• Fahrenheit
• Celsius
Gabriel Fahrenheit
• Kelvin
1686-1736
Anders Celsius
1701-1744
Lord Kelvin
(William Thomson)
1824-1907
3 Temperature Scales
Boiling point
of water
Freezing point
of water
Fahrenheit
Celsius
vin
212 ˚F
100 ˚C
373 K
180˚F
100˚C
32 ˚F
0 ˚C
100 K
273 K
Notice that 1 kelvin = 1 degree Celsius
Converting Between Scales
TK  T C + 273
TC 
T F
 32 
1.80
T C  TK  273
T F  1.80 T C  + 32
Calculations Using
Temperature
• Generally require temp’s in kelvins
• T (K) = t (˚C) + 273.15
• Body temp = 37 ˚C + 273 = 310 K
• Liquid nitrogen = -196 ˚C + 273 = 77 K
Fahrenheit Formula
F
= 9/5 °C + 32
°
Celsius Formula
(°F - 32) * 5/9
=
°C
Temperature Conversions
A person with hypothermia has a body
temperature of 29.1°C. What is the body
temperature in °F?
°F
=
9/5 (29.1°C) + 32
=
52.4 + 32
=
84.4°F
Learning Check
The normal temperature of a chickadee is
105.8°F. What is that temperature in °C?
1) 73.8 °C
2) 58.8 °C
3) 41.0 °C
Answer: 41 °C
Learning Check
Pizza is baked at 235 °C . What is that in °F?
1) 455 °f
2) 350°C
3) 400°C
Answer: 455 °F
Exercise
The normal body temperature for a
dog is approximately 102oF. What
is this equivalent to on the Kelvin
temperature scale?
a) 373 K
b) 312 K
c) 289 K
d) 202 K
Exercise
At what temperature does C = F?
Solution
•
•
Since °C equals °F, they both should be the
same value (designated as variable x).
Use one of the conversion equations such
as:
TC 
•
T F
 32 
1.80
Substitute in the value of x for both T°C and
T°F. Solve for x.
Solution
TC 
x
T F
 32 
1.80
x
 32 
1.80
x   40
So –40°C = –40°F