Unit 3 Review
Heat and Temperature
Topic 1:
Using Energy from Heat
What is Thermal Energy?
- the basic definition is heat
- used for cooking and keeping warm
- through the advancement of technology we have been able to control the use of thermal energy
- changes in needs and wants have advanced the uses of different thermal sources
Examples: clothesline drying to drying machine
drying hair naturally to hair dryers
Topic 2:
Measuring Temperature
Temperature
- defined as how hot or cold something is (this is the basic definitions BUT you must also know the scientific definition)
- may be estimated by touch and sight
Thermometers
- first thermometer invented by Galileo
- he invented the air thermometer on the basis that air expands when heated
- liquid use was then developed on the same premise
- mercury was used – did not stick to glass tubing and had appropriate freezing and boiling points
- alcohol thermometer most commonly used
Steps in Calibrating Thermometers
- in order for a thermometer to be accurate it must be calibrated
3 Steps:
1) freezing temperature (ice water)
2) boiling temperature
3) equal divisions marked between 2
points
Temperature Scales
Types:
1) Celsius Scale
2) Kelvin Scale
3) Fahrenheit Scale
** Review fixed temperatures and well known temperatures on all three scales – boiling point, freezing point,
body temperature, room temperature, absolute zero.
Thermometers
- different types of thermometers for different purposes
- each thermometer contains a sensor, signal and a responder
Types of Thermometers
1) Thermocouple
2) Bimetallic Strip
3) Recording Thermometer
4) Infrared Thermogram
** Refer to your notes and review over their uses and development.
Topic 3:
The Particle Model, Temperature and Thermal Energy
The Particle Model (How Particles Behave in a Substance)
4 main points
- all substances are made up of tiny particles too small to be seen
- constant motion
- spaces between particles
- motion of particles increases/decreases when the temperature increases/decreases
** Really understand the last point to the particle model of matter as you need to relate this point to the scientific definition
of temperature and thermal energy
Three States of Matter
- solid, liquid and gas
- behaviour of particles act differently in each state (movement, shape and volume)
- refer to your reading assignment about how these particles behave in each of their states
Thermal Energy (Heat)
- energy that flows to or from a substance
- transferred from hot to cold
- total kinetic energy
- the faster the particle motion the higher the thermal energy
- measured in Joules
Temperature
- particle motion and temperature are directly related
- increase in temperature increases particle motion and vice versa
- the average speed (average kinetic energy) of particles in motion
- measured in degrees Celsius
** Look back and review over the tea cup and pail example – Eureka video – the difference between thermal energy and
temperature… why is there a difference…
Energy
-
something’s ability to do work or to cause change (example: charged battery)
energy is transferred or transformed from one energy type to another (electricity to light)
does not have mass
cannot be created or destroyed
it is a state, quality or a condition
energy transfers in one direction (high to low OR hot to cold)
Law of Conservation of Energy
Topic 4: Expansion and Contraction
Expansion
- as thermal energy is added the particles move faster and spread apart, causing an increase in volume
Contraction
- as thermal energy is removed the particles slow down and move closer together, causing a decrease in volume
Expansion and Contraction of Solids
- all solids expand and contract at different rates when heated and cooled
- each solid has a unique characteristic (eg. copper, steel and concrete)
- solids expand very slowly as compared to liquids and gases due to the strong bonds between the particles
- the small change adds up in relation to large structures therefore expansion and contraction rates of materials must
be considered in construction
- refer to lab examples – bimetallic strip and ball and ring
Expansion and Contraction of Gases
- particles in gases are farther apart than those in solids and the forces of attraction are much weaker
- any increase in temperature will causes the gas particles to move rapidly away from each other, so gases expand
more than solids given the same temperature change
- refer to lab examples – balloon and flask
Expansion and Contraction of Liquids
- all liquids expand and contract at different rate (eg. mercury, alcohol, oil, water, vinegar)
- refer to lab example – heart meter
**Think of everyday examples of expansion and contraction – railroads, bridges, buildings, expansion joints,
sidewalks, bowl of soup, hot air balloons, telephone wires… etc.
Topic 5: The Particle Model and Changes of State
Heat Capacity
- the amount of thermal energy that warms or cools an object by one degree Celsius
Types:
a) Low Heat Capacity – objects that warm and cool quickly (sand example)
b) High Heat Capacity – objects that warm and cool slowly (water example)
Changes of State
The six changes of state include:
1) solidification – liquid to solid
2) fusion – solid to liquid
3) condensation – gas to liquid
4) evaporation – liquid to gas
5) sublimation – solid to gas
6) sublimation – gas to solid
-
any pure substance can exist in all three states of matter
during a phase change the temperature stays constant (hidden or latent heat)
particles become less organized as their energy increases (solid-liquid-gas)
particles become more organized as their energy decreases (gas-liquid-solid)
** Refer to diagram/graph in notes to explain what happens to the organization of particles as their energy
increases/decreases.
Evaporative Cooling
- the phenomenon that as particles evaporate they become cooler
- fast moving particles (warm) escape leaving behind slow moving particles (cool)
- any surface it comes in contact with cools as well (example: perspiring)
Topic 6:
Transferring Energy
Three ways that energy can be transferred are:
1. Radiation
2. Conduction
3. Convection
Radiation
- transfer of energy without any movement of matter (radiant energy or electromagnetic radiation – EMR)
- radiant energy travels like a wave (ripple action)
- can travel through empty space, air, glass and other materials
- examples include radio waves, microwaves, visible light, x-rays and the sun’s energy (heat radiation)
Common Characteristics of Radiant Energy
- behave like waves
- can be absorbed or reflected
- travel across space at a very high speed (300 000 km/s)
Conduction
- the transferring of thermal energy from one particle to another (collision/colliding of particles)
- conduction occurs in solids
- particles in liquids and gases are too far apart for conduction to take place
- some solids are excellent conductors (gold, copper) because they allow the transfer of energy
- some solids are poor conductors (glass, wood) because they prevent the transfer of energy – these are called
insulators
- R-Value is a measurement used on insulators to know the degree to which it is an effective insulator – the higher the
value the better the insulator
Convection
- a continuous cycle of warm fluid or particles rising from a heat source, cooling and sinking back down toward the heat
source ( the process repeats)
- examples of the use of this process is seen in a furnace, boiler, stove and dryer
Features of Energy Transfer Systems
1. Energy Source
2. Direction of Energy Transfer
3. Transformations
4. Waster Heat
5. Control Systems
** Refer to your reading assignment for an explanation of each of the following features of energy transfer
systems. There are also examples in your reading assignment.
Topic 7:
Sources of Thermal Energy
Types of Thermal Energy
1)
-
Chemical Energy
the energy stored in food and fuels
heat is released from food and fuels through a chemical process of burning
food is digested releasing energy
fuels, such as wood, coal and other fossil fuels burn to release energy
2)
-
Electrical Energy
energy stored in moving water can be used to generate electricity (hydroelectricity)
produced at generating stations that burns fuels to produce electricity
electricity is sent to homes and industries through a system of wires
this type of energy production has caused negative effects on the environment
3) Mechanical Forces
- thermal energy produced by the force of friction (the rubbing of two objects)
- mechanical forces that push and pull objects release thermal energy (car brakes, bicycle brakes, skidding tires)
4) Geothermal Energy
- energy that is harnessed from the Earth’s interior
- examples include erupting volcanoes, geysers and hot springs
- good, clean and reliable energy source
5) Solar Energy
- energy from the Sun
- clean and a resource that will always be available, however inventions are continually being created to harness this
great power
6) Wind Energy
- energy of moving air
- created by convection currents
- windmill invention has been used to capture the power of the wind to generate electricity
Define:
1. energy resource
2. fossil fuels
3. non-renewable resources
4. renewable resources
5. thermal pollution
6. cogeneration
Topic 8:
Conserving Our Fossil Fuel Resources
- fossil fuels are important part of our economy, but the burning of them has created so many disadvantages
- we believed that this resource was readily available and that the environmental effects were minimal
- this idea has changed as scientists have done more research
Danger: Thermal Energy
- harmful effects obvious (forest fires, pollution)
- industries responsible for containing and storing dangerous chemicals and products
By-Products of Thermal Energy Use
1) Carbon Dioxide
- burning of fossil fuels (cause of global warming)
2) Sulfur Dioxide
- irritant to eyes, nose and throat
- companies and industries put a lot of money into research to reduce these emissions
3) Carbon Monoxide
- lethal gas – poisons brain – inability to reason and function
Knowledge of the dangers of thermal energy will help you make proper environmental choices.
Questions:
1.
What is the basic definition of thermal energy?
Answer: heat
2.
What are the two main uses of thermal energy?
Answer: cooking and heating
3.
What are the two ways that temperature may be estimated?
Answer: touch and sight
4.
Who invented the first thermometer?
Answer: Galileo
5.
What was the name of Galileo’s first thermometer?
Answer: air thermometer
6.
What are the two most common liquids used in laboratory thermometers?
Answer: alcohol and mercury
7.
How may the accuracy of the Celsius scale be affected?
Answer: pressure, sea level and impurities of water
8.
What are the three steps in calibrating a thermometer?
Answer: set freezing points and boiling points and divide into equal divisions
9.
Name three temperature scales.
Answer: Celsius, Kelvin, Fahrenheit
10. What scale is used for scientific measurements?
Answer: Kelvin
11.
What is the freezing point of water on the Celsius scale?
Answer: 0C
12. What is the boiling point of water on the Celsius scale?
Answer: 100C
13. What is absolute zero?
Answer: coldest possible temperature
14. What is absolute zero in degrees Celsius? Kelvin?
Answer: Celsius is –273.15C and Kelvin is 0 K.
15. What are the three main parts of every thermometer?
Answer: sensor, signal, responder
16. What thermometer produces an electrical current?
Answer: thermocouple
17. This measuring device is used to turn on and off an electrical switch.
Answer: bimetallic strip
18. Used to measure temperature over a long period of time.
Answer: recording thermometer
19. This thermometer uses infrared radiation and color to indicate temperature.
Answer: infrared thermogram
20. What is body temperature in the Fahrenheit scale?
Answer: 96F
21. What are the four main points of the particle model of matter?
Answer: all substances are made of particles, constant motion, spaces, motion of particles is related to temperature
22. Thermal energy is measured in this standard unit.
Answer: Joule
23. What direction does energy flow?
Answer: high energy to low energy or hot to cold
24. What is the scientific definition of temperature?
Answer: the average speed of particles in motion
25. What is energy?
Answer: something’s ability to do work
26. What is expansion?
Answer: increase in volume
27. What is contraction?
Answer: decrease in volume
28. What are the key characteristics of an object with low heat capacity?
Answer: warms and cools quickly
29. What are the key characteristics of an object with high heat capacity?
Answer: warms and cools slowly
30. What is solidification?
Answer: liquid to solid
31. What is fusion?
Answer: solid to liquid
32. What is condensation?
Answer: gas to liquid
33. Name the change of state from liquid to gas.
Answer: evaporation
34. Name the change of state that bypasses the liquid state.
Answer: sublimation
35. What happens to the temperature of a substance during a phase change?
Answer: stays constant
36. What is the name of the phenomenon in which particle cool as they evaporate?
Answer: evaporative cooling
37. What is latent heat or hidden heat?
Answer: at the point where a substance changes from one state to another, heat cannot be detected, on a graph it is represented by a
plateau (the particles are going through a rearrangement from a sold to a liquid to a gas OR a gas to a liquid to a solid)
37. What does EMR stand for?
Answer: electromagnetic radiation
38. What are the three ways that energy may be transferred?
Answer: radiation, convection, conduction
39. What are the three characteristics that all types of radiant energy share?
Answer: behave like waves, can be absorbed or reflected, travel at high speeds
40. Name two examples of radiant energy.
Answer: microwaves, x-rays, visible light, radio waves, sunlight
41. Of what state of matter does conduction occur?
Answer: solid
42. What is the special name given to those materials that are not good conductors?
Answer: insulators
43. What solid types are the best conductors?
Answer: metals
44. What is convection?
Answer: the continuous cycle of warm air rising, cooling and returning to the energy source
45. Where or how are convection currents used?
Answer: furnace, stove, dryer, winds and breezes
46. List 5 features that all energy transfers have in common.
Answer: energy source, direction, transformation, waste heat and control system
47. What is chemical energy?
Answer: energy stored in food and fuels
48. What type of electricity is produced by moving water?
Answer: hydroelectricity
49. What is an example of mechanical forces?
Answer: car brakes, tires skidding, nail pounding – anything related to friction
50. What is geothermal energy?
Answer: energy that is harnessed from the Earth’s surface
51. What is solar energy?
Answer: energy from the sun
52. What is nuclear energy?
Answer: through nuclear fission small amounts of radioactive uranium is used to produce vast amounts of heat
53. What is active solar energy?
Answer: active solar heating uses mechanical devices like fans to distribute stored thermal energy – heating that requires a mechanical
device to carry heat to other parts of the building
54. What is passive solar energy?
Answer: passive solar heating uses the materials in the structure to absorb, store and release solar energy – direct heating by the sun’s
rays, without fans, pumps or pumps to carry the heat to other parts of the building
55. How can wind energy be harnessed?
Answer: windmills
56. What is a non-renewable resource?
Answer: resources that once gone are gone forever (takes a long period of time to replace)
57. What is a renewable resource?
Answer: resources that can be recycled or replaced
58. What are greenhouse gases?
Answer: gases, such as carbon dioxide, that result from the burning of fossil fuels or wood; greenhouse gases prevent heat from leaving
the atmosphere, increasing the temperature of the atmosphere
59. What is cogeneration?
Answer: a method of energy conservation by which waste heat or energy from one industry is used by another
60. What is thermal pollution?
Answer: a warming of the environment as a result of human activities, such as burning of fossil fuels
61. What are three negative by-products of thermal energy?
Answer: carbon dioxide, sulfur dioxide, carbon monoxide
62. What is matter?
Answer: anything that takes up space, has mass and is made up of particles
63. Does energy have mass?
Answer: NO
64. What state of matter fills the container in which is was placed?
Answer: gas
65. What state of matter has a definite size, but no fixed shape?
Answer: liquid
66. What is a pure substance?
Answer: a material that is composed of only one type of particle