Chapter 5 Worksheet



Grade 7 Science: Unit 2 – Heat

Chapter 5 Review Sheet

Name: ________ANSWERS_________

1. (a) Gives THREE (3) examples of matter.

Book, pencil, humans, etc– anything that takes up space and has mass.

(b) Give an example of something that is NOT matter.

Fire, gravity, the month of June, radiation, etc.

2. List the FIVE (5) parts of the Particle Theory of Matter.

• All matter is made up of tiny particles.

• These particles are always moving – they have energy. The more energy particles have the faster they move.

• There is space between all particles.

• There are attractive forces between the particles.

• The particles of one substance differ from the particles of other substances.

3. (a) What is kinetic energy?

The energy of motion/movement.

(b) What are the possible units that we can use to measure kinetic energy?

Joules (J), m/s, Km/s, etc

(c) How do you calculate the average kinetic energy of particles?

Add up all of the kinetic energies and divide by the number of energies that are given.

(d) Find the average kinetic energy of the particles with the following energies:

|Workings: |

|15 J + 12 J + 3 J = 30 J |

|30 J ÷ 3 = 10 J |

| |

(e) Do all particles in the same room have the same kinetic energy? Explain.

No, since some particles can have a higher temperature than other particles, their kinetic energies will not be the same. Remember the following relationship: the higher the temperature of the particles, the higher their kinetic energy of the particles (and vice versa).

Additionally, the room will be made up of particles of solids, liquids and gases, which will determine how quickly they will be moving. Solids will be only vibrating, liquids will be moving at a medium speed (sliding past one another) and gases will be moving extremely fast.

4. Fill in the table below regarding the three states of matter.

| | | | |

| |____Solid______ |_____Liquid_____ |____Gas______ |

| |[pic] |[pic] | |

| | | | |

|Volume | |Stays the same (Fixed) |Changes – gases will always |

| |Stays the same (Fixed) | |expand to fill the container |

| | | |completely |

| | | | |

|Shape | |Changes to take the shape of | |

| |Stays the same (Fixed) |container |Changes to take the shape of |

| | | |container |

| | | | |

|Particle Arrangement |Very Close |Close – able to slide past one |Far apart |

| | |another | |

| | | | |

|Particle Movement |Slow/Vibrating |Medium Speed |Fast – Very Fast |

5. (a) What happens to the particles of a substance when the substance expands?

The particles move outward (i.e. further away from each other), take up as much space as possible and their attractive forces become weaker. This is experienced during heating – expect when ice freezes.

(b) What happens to the particles of a substance when the substance contracts?

The particles move closer to one another, take up as less space as possible and their attractive forces become stronger. This is experienced during cooling.

6. (a) Fill in the table below regarding the changes of state. Hint – the first one is completed for you.

|Changes of State |Description |

|Sublimation |The change of state from a solid to a gas. |

|Deposition |The change of state from a gas to a solid. |

|Evaporation |The change of state from a liquid to a gas. |

|Condensation |The change of state from a gas to a liquid. |

|Freezing |The change of state from a liquid to a solid. |

|/Solidification | |

|Melting |The change of state from a solid to a liquid. |

(b) In the table below, illustration what is happening to the particles during each phase change. You will need to show how the particles look just before and after the phase change has occurred.

|Changes of State |Illustrations |

| | [pic] |

|Melting | |

|(Heat required) | |

| | |

|Freezing | |

|(Cooling Required) | |

| | |

|Evaporation | |

|(Heat required) | |

7. (a) What is a heating curve?

A heating curve shows how the temperature of water changes as more heat energy is added. When water is melting or evaporating (i.e. change of state) the temperature remains constant/unchanging.

(b) Label the parts of the heating curve.

[pic]

1. Solid

2. Melting

3. Liquid

4. Evaporation/Boiling

5. Gas

(c) As heat is being added, what is happening to the kinetic energy of the particles?

The particles are being more excited, meaning they are speeding up, moving further away from each other and losing their attractive forces.

(d) As the particles goes through section (2), what is happening to the distance between the particles?

The distance between the particles is increasing, as the ice is melting.

(e) Describe what is happening to the temperature during section (2) and section (4).

The temperature remains constant (i.e. stays the same) as the phase change is happening.



8. All matter is made up of particles. All particles contain even smaller components called electrons that can, when excited, move away from the particles, thus passing on their energy as heat. The particles in metal are very close together, and thus can easily pass on these electrons, causing the metal to quickly rise in temperature. This is why metal’s are great conductors of electricity. The table below shows how the number of moving electron’s can affect the temperature of a metal.

|Number of Electrons |Temperature (oC) |

|20 |35 |

|40 |54 |

|60 |76 |

|80 |82 |

|100 |95 |

|120 |115 |

A. What is the independent (manipulated) variable?

Number of Electrons

B. What is the dependent (responding) variable?

Temperature (oC)

C. Create a fully labelled line graph on the grid below based on the information provided in the table.

[pic]

D. What would you predict as the temperature of the metal when there are 110 electrons? Briefly explain how you got this number.

The approximate temperature of the metal is about 102 – 108 oC. See graph below.

E. What is the relationship between the number of electrons and the temperature of the metal in this case study?

As the number of electron’s increases, the temperature of the metal increases (and vice versa). [pic]

-----------------------

12 J

3 J

15 J

After

Before

[pic]

[pic]

[pic]

[pic]

[pic]

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