CHAPTER 3 Temperatu re Energy and Heat 3.1 Temperature
CHAPTER 3 Temperature Energy and Heat 3.1 Temperature.
Jan 21, 2016
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CHAPTER 3
Temperature Energy and
Heat
3.1 Temperature
2 3.1 Temperature
• What is temperature?
• Why is temperature important in chemistry?
• How is energy related to temperature?
3 3.1 Temperature
Milk fat particles are being pushed around by water molecules
4 3.1 Temperature
At room temperature, atoms and molecules are in constant motion
Brownian motion
Milk fat particles are being pushed around by water molecules
5 3.1 Temperature
Grains of sand stand still…
6 3.1 Temperature
Grains of sand stand still…
… but the individual atoms are in constant, random motion.
kinetic energy: the energy of motion.
temperature: a measure of the average kinetic energy of atoms or molecules.
7 3.1 Temperature
Random motion
AFFECTS
temperature
Non random motion
DOES NOT AFFECT
temperature
Random motion Non random motion
8 3.1 Temperature
Temperature is the measure of
the average kinetic energy of
atoms or molecules
Some molecules have more kinetic energy than the average.
Some molecules have less kinetic energy than the average.
Temperature is an average
Faster(more energy)
Slower(less energy)
9 3.1 Temperature
Temperature is the measure of
the average kinetic energy of
atoms or molecules
Some molecules have more kinetic energy than the average.
Some molecules have less kinetic energy than the average.
Temperature is an average
10 3.1 Temperature
Does everyone express temperature the same way?
11 3.1 Temperature
Temperature scales
12 3.1 Temperature
Water boils
Water freezes
How can we go back and forth between the two scales?
Temperature scales
13 3.1 Temperature
What temperature in Celsius is the same as 100oC?
14 3.1 Temperature
What temperature in Celsius is the same as 100oF?
Asked: Temperature in oC
Given: 100oF
Relationships: 532
9C FT T
15 3.1 Temperature
Asked: Temperature in oC
Given: 100oF
Relationships:
Solve:
Answer: 100oF is the same temperature as 37.8oC
532
9C FT T
5 5100 32 68
937.8
9o
C CT
What temperature in Celsius is the same as 100oF?
16 3.1 Temperature
Asked: Temperature in oF
Given: 15oC
Relationships:5
329F cT T
What is the Fahrenheit equivalent of 15oC?
17 3.1 Temperature
Asked: Temperature in oF
Given: 15oC
Relationships:
Solve:
Answer: 15oC is the same temperature as 59oF.
532
9F cT T
515 32 27 32
959oFT F
What is the Fahrenheit equivalent of 15oC?
18 3.1 Temperature
Hot or cold?
How can we accurately measure temperature?
19 3.1 Temperature
All thermometers are based on a physical property that changes with temperature.
Thermal expansion:- Mercury thermometers- Alcohol thermometers
Electrical sensors:- Thermistor- Thermocouple
20 3.1 Temperature
Thermal expansion:- Mercury thermometers- Alcohol thermometers
Electrical sensors:- Thermistor- Thermocouple
The temperature probe in the Lab-Master uses
a thermistor
All thermometers are based on a physical property that changes with temperature.
21 3.1 Temperature
kinetic energy: the energy of motion.
temperature: a measure of the average kinetic energy of atoms or molecules.
22 3.1 Temperature
kinetic energy: the energy of motion.
temperature: a measure of the average kinetic energy of atoms or molecules.
What happens when the temperature is really, really low?
What is the lowest possible temperature?
23 3.1 Temperature
Absolute zero
At absolute zero the
kinetic energy is
essentially zero.
3 different scales
24 3.1 Temperature
We have already seen:
932
5Fahrenheit CelsiusT T
532
9Celsius FahrenheitT T
Unit conversion
25 3.1 Temperature
+ 273
- 273
273Kelvin CelsiusT T
Unit conversion
26 3.1 Temperature
Convert 27oC into kelvins.
Unit conversion
27 3.1 Temperature
Convert 27oC into kelvins.
Asked: Temperature in kelvin
Given: 27oC
Relationships: 273Kelvin CelsiusT T
Unit conversion
28 3.1 Temperature
Convert 27oC into kelvins.
Asked: Temperature in kelvin
Given: 27oC
Relationships:
Solve:
Answer: 300 K is the same temperature as 27oC.
273Kelvin CelsiusT T
27 273 300KT K
Unit conversion
29 3.1 Temperature
932
5Fahrenheit CelsiusT T
532
9Celsius FahrenheitT T
273Kelvin CelsiusT T
Molecules are in constant, random motion.
This affects temperature.
Three temperature scales:
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