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8/12/2019 2.2 Temperature
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 1
Temperature
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 2
Temperature
Temperature
is a measure of how hot or cold an
object is compared to another
object indicates that heat flows from the
object with a higher temperature to
the object with a lower temperature
is measured using a thermometer
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 3
Temperature Scales
Temperature scales
are Fahrenheit,
Celsius, and Kelvin
have referencepoints for the boiling
and freezing points
of water
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 4
A. What is the temperature of freezing water?
1) 0 °F 2) 0 °C 3) 0 K
B. What is the temperature of boiling water?1) 100 °F 2) 32 °F 3) 373 K
C. How many Celsius units are between the boiling and
freezing points of water?
1) 100 2) 180 3) 273
Learning Check
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 5
A. What is the temperature of freezing water?
2) 0 °C
B. What is the temperature of boiling water?3) 373 K
C. How many Celsius units are between the boiling and
freezing points of water?
1) 100
Solution
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 6
On the Fahrenheit scale, there are 180 °F between the
freezing and boiling points, and on the Celsius scale,
there are 100 °C.
180°F = 9
°F = 1.8
°F
100 °C 5 °C 1 °C
In the formula for the Fahrenheit temperature, adding
32 adjusts the zero point of water from 0 °C to 32 °F.
TF = 9 (TC ) + 32° 5
or TF = 1.8(TC ) + 32 °
Fahrenheit Formula
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 7
TC is obtained by rearranging the equation for T
F .
TF = 1.8(T
C ) + 32 °
Subtract 32 from both sides.
TF –
32 ° = 1.8(TC) + (32 ° –
32 °)TF – 32 ° = 1.8(TC )
Divide by 1.8. TF – 32 ° = 1.8 T
C
1.8 1.8
TF – 32 ° = TC
1.8
Celsius Formula
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 8
Solving a Temperature Problem
A person with hypothermia has a
body temperature of 34.8 °C. What
Is that temperature in °F?
TF = 1.8(T
C ) + 32 °
TF = (1.8)(34.8 °C) + 32 °
exact tenth’s exact
= 62.6 ° + 32 °
= 94.6 °Ftenth’s
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 9
The normal temperature of a chickadee is 105.8 °F.
What is that temperature on the Celsius scale?
1) 73.8 °C
2) 58.8°C
3) 41.0 °C
Learning Check
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 10
The normal temperature of a chickadee is 105.8 °F.
What is that temperature on the Celsius scale?
3) 41.0 °C
TC = TF –
32 ° 1.8
= (105.8 – 32 °)
1.8
= 73.8 °F = 41.0 °C
1.8 ° tenth’s place
Solution
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 11
A pepperoni pizza is baked at 455 °F. What
temperature is needed on the Celsius scale?
1) 423 °C
2) 235°C
3) 221 °C
Learning Check
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 12
A pepperoni pizza is baked at 455 °F. What
temperature is needed on the Celsius scale?
2) 235 °C
TF –
32° = TC
1.8
(455 – 32 °) = 235 °C
1.8 one’s place
Solution
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
13
On a cold winter day, the temperature is –15 °C.
What is that temperature in °F?
1) 19 °F
2) 59°F
3) 5 °F
Learning Check
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 14
3) 5 °F
TF = 1.8T
C + 32 °
TF = 1.8( –
15 °C) + 32 ° = – 27 + 32 °
= 5 °F
one’s place
Note: Be sure to use the change sign key onyour calculator to enter the minus ( –) sign.
1.8 x 15 +/ – = –27
Solution
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 15
The Kelvin temperature
is obtained by adding 273 to the Celsius temperature
TK = TC + 273
In the Kelvin temperature scale:
There are 100 units between the freezing and boiling
points of water.
100 K = 100 °C or 1 K = 1 °C 0 K (absolute zero) is the lowest possible
temperature.
0 K = –273 °C
Kelvin Temperature Scale
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 16
Temperatures
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 17
What is normal body temperature of 37 °C in kelvins?
1) 236 K
2) 310 K
3) 342 K
Learning Check
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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 18
What is normal body temperature of 37 °C in kelvins?
2) 310 K
TK = TC + 273= 37 °C + 273
= 310. K
one’s place
Solution