temperature & heat - casquete-utpa -...
TRANSCRIPT
![Page 1: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/1.jpg)
Temperature & Heat
Physical Science Chapter 5 Cont2
![Page 2: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/2.jpg)
What are we going to study?
Temperature
Heat
Specific Heat and Latent Heat
Heat Transfer
Phases of Matter
The Kinetic Theory of Gases
Thermodynamics
![Page 3: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/3.jpg)
Chapter 5: Temperature
“Hot” & “Cold” are relative terms.
Temperature depends on the kinetic (motion) energy of the molecules of a substance.
Temperature is a measure of the average kinetic energy of the molecules of a substance.
Section 5.1
![Page 4: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/4.jpg)
Thermometer
Thermometer - an instrument that utilizes the physical properties of materials for the purpose of accurately determining temperature
Section 5.1
![Page 5: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/5.jpg)
Thermometer
Thermal expansion is the physical property most commonly used to measure temperature. – Expansion/contraction of metal
– Expansion/contraction of mercury or alcohol
Section 5.1
![Page 6: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/6.jpg)
Bimetallic Strip and Thermal Expansion
Brass expands more than iron.
The degree of deflection is proportional to the temperature.
A/C thermostat and dial-type thermometers are based on bimetal coils.
Section 5.1
![Page 7: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/7.jpg)
Liquid-in-glass Thermometer
Thermometers are calibrated to two reference points (ice point & steam point.) – Ice point – the temperature of a mixture of
pure ice and water at normal atmospheric pressure
– Steam point – the temperature at which pure water boils at normal atmospheric pressure
Usually contains either mercury or red (colored) alcohol
Section 5.1
![Page 8: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/8.jpg)
Temperature Scales Celsius, Kelvin, Fahrenheit
Section 5.1
![Page 9: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/9.jpg)
Temperature Scales Celsius, Kelvin, Fahrenheit
Scale Absolute
Zero
Ice
Point
Steam
Point
Diff.
(Boil –
Ice)
Fahrenheit - 460o 32o 212o 180
Celsius -273o 0o 100o 100
Kelvin 0o 273o 373o 100
Section 5.1
![Page 10: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/10.jpg)
Converting Temperatures is Easy!
TK = TC + 273 (Celsius to Kelvin)
TC = TK – 273 (Kelvin to Celsius)
TF = 1.8TC + 32 (Celsius to Fahrenheit)
Section 5.1
TF – 32
1.8 • TC = (Fahrenheit to Celsius)
![Page 11: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/11.jpg)
Converting a Temperature Example # 1
Convert the Celsius temperature of -30oC into Fahrenheit.
EQUATION: TF = 1.8TC + 32
Section 5.1
![Page 12: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/12.jpg)
Thermal Energy and Heat Temperature – a measure of the AVERAGE kinetic
energy of the individual particles of a substance.
Temperature – Perception of how cold or hot something
is.
Thermal energy – TOTAL energy of all of the particles
![Page 13: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/13.jpg)
Heat
Kinetic and Potential energy both exist at the molecular level. – Kinetic – motion of molecules
– Potential – bonds that result in the molecules oscillating back and forth
Heat is energy that is transferred from one object to another as a result of a temperature difference.
Heat – thermal energy moving from a warmer object to a cooler object, trying to reach thermodynamic equilibrium.
Section 5.2
![Page 14: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/14.jpg)
Heat Unit SI - Calorie Since heat is energy, it has a unit of joules. (J)
A more common unit to measure heat is the calorie.
Calorie - the amount of heat necessary to raise one gram of pure water by one Celsius degree at normal atmospheric pressure
1 cal = 4.186 J (or about 4.2 J)
Kilocalorie – heat necessary to raise 1kg water by 1oC
1 food Calorie = 1000 calories (1 kcal)
1 food Calorie = 4186 J (or about 4.2 kJ)
Section 5.2
![Page 15: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/15.jpg)
Heat Unit British - Btu
British thermal unit (Btu) – the amount of heat to raise one pound of water 1oF
1 Btu = 1055 J = 0.25 kcal = 0.00029kWh
A/C units are generally rated in the
number of Btu’s removed per hour.
Heating units are generally rated in the number of Btu’s supplied per hour.
Section 5.2
![Page 16: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/16.jpg)
1. Energy in transit because of a temperature difference
2. The same as temperature
3. The internal energy of a substance
4. Unrelated to energy
0%
0%
0%
0%
Conceptual Question 1: Which of the following phrases best describes heat?
![Page 17: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/17.jpg)
1. Energy is transferred from the cold object to the hot object
2. Energy is transferred from the hot object to the cold object
3. The temperature is transferred from cold object to hot object
4. The temperature is transferred from hot object to cold object
0%
0%
0%
0%
Conceptual Question 2: How does the energy is transferred?
![Page 18: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/18.jpg)
5 | 18
Example 2
How much energy have you gained after eating a peanut that contains 10 Calories?
Section 5.2
![Page 19: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/19.jpg)
Heat vs. Temperature
http://www.youtube.com/watch?v=NVXLDPHGYhg
![Page 20: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/20.jpg)
Expansion/Contraction with D’s in Temperature
In general, most matter, solids, liquids, and gases will expand with an increase in temperature (and contract with a decrease in temperature.)
Water is an exception to this rule – (ice floats!)
Section 5.2
![Page 21: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/21.jpg)
Thermal-Expansion Joints in a Bridge
These joints allow for the contraction and expansion of the steel girders during the winter and summer seasons.
Section 5.2
![Page 22: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/22.jpg)
Behavior of Water Strange!
The volume of a quantity of water decreases with decreasing temperature but only down to 4oC. Below this temperature, the volume increases slightly.
With a minimum volume at 4oC, the density of water is maximum at this temperature and decreases at lower temperatures.
Most dense point
Section 5.2
![Page 23: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/23.jpg)
Behavior of Water: Structure of Ice Solid water takes up more volume
a) An illustration of the open hexagonal (six-sided) molecular structure of ice.
b) This hexagonal pattern is evident in snowflakes.
Section 5.2
(Ebbing, Darrell D., General Chemistry, Sixth Edition. Copyright 1999 by Houghton Mifflin Company)
![Page 24: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/24.jpg)
Behavior of water
Liquid water below 4 C is bloated with ice crystals.
Upon warming, the crystals collapse, resulting in a smaller volume for the liquid water.
Above 4oC liquid water expands as it is heated because of greater molecular motion.
Section 5.3
![Page 25: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/25.jpg)
5 | 25
Yellowstone Lake - Frozen
Photo Source: Copyright © Bobby H. Bammel. All rights reserved.
Section 5.2
Do you know that fish live below frozen lakes? How?
![Page 26: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/26.jpg)
1. Specific heat capacities
2. Energy at different temperatures
3. Rates of thermal expansion
4. All of these
0%
0%
0%
0%
Conceptual Question 3: A bimetallic strip used in thermostats relies on the
fact that different metals have different…
![Page 27: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/27.jpg)
Specific Heat (Capacity)
If equal quantities of heat are added to equal masses of two metals (iron and aluminum, for example) – would the temperature of each rise the same number of degrees? -- NO!
Different substances have different properties.
Specific Heat – the amount of heat necessary to raise the temperature of one kilogram of the substance 1oC
Section 5.3
![Page 28: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/28.jpg)
Specific Heat (Capacity)
The greater the specific heat of a substance, the greater is the amount of heat required to raise the temperature of a unit of mass.
Put another way, the greater the specific heat of a substance the greater its capacity to store more heat energy
Water has a very high heat capacity, therefore can store large amounts of heat.
Section 5.3
![Page 29: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/29.jpg)
1. Absorbs great quantity of heat for small increases of temperature
2. Absorbs great quantity of heat for a big increases of temperature
3. Absorbs a small quantity of heat for small increases of temperature
4. Absorbs a small quantity of heat.
0%
0%
0%
0%
Conceptual Question 4: Water is useful in the cooling systems of automobiles, and other engines because it …
![Page 30: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/30.jpg)
Specific Heats of Some Common Substances
The three phases
of water are
highlighted.
Section 5.3
![Page 31: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/31.jpg)
5 | 31
Sand (700 J/kg-Co) & Water (4186 J/kg-Co)
Photo Source: Copyright © Bobby H. Bammel. All rights reserved.
Section 5.3
![Page 32: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/32.jpg)
Specific Heat Capacity
Youtube: http://www.youtube.com/watch?v=hyPLusD-tyM
Demonstration:
![Page 33: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/33.jpg)
Specific Heat Depends on Three Factors
The specific heat or the amount of heat necessary to change the temperature of a given substance depends on three factors:
1) The mass (m) of the substance
2) The heat (c) of the substance
3) The amount of temperature change (DT)
Section 5.3
![Page 34: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/34.jpg)
Using Specific Heat
H = mcDT
– H = amount of heat to change temperature
– m = mass
– c = specific heat capacity of the substance
– DT = change in temperature
The equation above applies to a substance that does not undergo a phase change.
Section 5.3
![Page 35: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/35.jpg)
Example: Using Specific Heat
How much heat in kcal does it take to heat 80 kg of bathwater from 12oC to 42oC?
GIVEN: m = 80 kg, c = 1.00 kcal/kg.Co (known value for water)
Section 5.3
![Page 36: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/36.jpg)
5 | 36
Example: How much it costs to heat the bath
water electrically?
Heat needed = 2.4 x 103 kcal
Convert to kWh
1kcal = 0.00116kWh
At 12 cents per kWh, it will cost ??
Section 5.3
![Page 37: Temperature & Heat - casquete-utpa - HOMEmarthacasqueteutpa.weebly.com/uploads/2/0/9/9/20997728/... · 2019. 9. 8. · Chapter 5: Temperature “Hot” & “Cold” are relative terms](https://reader035.vdocuments.site/reader035/viewer/2022071423/611e3f3005bba2599f501b4a/html5/thumbnails/37.jpg)
Using Specific Heat Confidence Exercise
How much heat needs to be removed from a liter of water at 20oC so that is will cool to 5oC ?
GIVEN: 1 liter water = 1 kg = m
DT = 15oC; c = 1.00 kcal/kg.Co
Section 5.3