Physical And Chemical Change

Question 1

Define physical change

Answer 1

A physical change is a change in which no new substance is formed.

Question 2

Describe examples of physical change.

Answer 2

Examples of physical change include
changes in shape,
expansion and contraction,
changes of states,
mixing.

Question 3

How does water behave when it freezes?

Answer 3

Water expands when it freezes, which causes ice to float.

Question 4

What happens to metals when they are heated?

Answer 4

Metals expand when heated.

Question 5

Describe the process of melting.

Answer 5

Melting is the process that causes a substance to change from a solid to a liquid, occurring when the molecules of a solid speed up enough to overcome attractions and move past each other.

Question 6

What is freezing?

Answer 6

Freezing is the process that causes a substance to change from a liquid to a solid, occurring when the molecules of a liquid slow down enough to arrange themselves into fixed positions.

Question 7

How does evaporation occur?

Answer 7

Evaporation is the process that changes liquid water to gaseous water (water vapour).

Question 8

Define condensation

Answer 8

Condensation is the process of water vapour turning back into liquid water.

Question 9

Describe the contraction of materials.

Answer 9

Contraction can be observed in phenomena such as the snapping of taut power lines in winter, deflation of balloons in cold water, and breakage of hot glass under cold water.
Most things contract when they are cooled

Question 10

Describe ways to detect the presence of a new substance.

Answer 10

Five different signs include odour, temperature change, precipitate formation, production of gas bubbles, and colour change.

Question 11

Describe some examples of colour change that indicate chemical change.

Answer 11

Examples include the rusting of metal, which changes to orange, and vinegar turning red when an indicator solution is added.

Question 12

Describe examples of gas formation that are chemical.

Answer 12

An example is the reaction between baking soda and an acid (like lemon juice or vinegar), which produces bubbles of carbon dioxide (CO2).

Question 13

Describe the structure of solids.

Answer 13

Solids have a 3-dimensional arrangement of atoms, ions, or molecules that are locked into position, with all components touching and stuck in place.

Question 14

Describe the structure of liquids.

Answer 14

Liquids have a structure that is intermediate between gases and solids, where atoms, ions, and molecules touch and flow freely, lacking the ordered structure of solids.

Question 15

Describe the structure of gases.

Answer 15

Gases consist of a large number of atoms and molecules that move randomly and are spread apart from each other.

Question 16

Describe particle behaviour when substances expand and contract.

Answer 16

As particles gain thermal energy, they collide more often, move faster, and travel further apart.

Question 17

Describe the process of freezing using the particle model.

Answer 17

Freezing occurs when the molecules in a liquid slow down enough to change their state to the fixed 3D arrangement of a solid.

Question 18

Explain how melting is represented in the particle model.

Answer 18

Melting occurs when the molecules in a solid speed up enough so that their motion overcomes the attractions, allowing them to move past each other as a liquid.

Question 19

How does evaporation occur according to the particle model?

Answer 19

Evaporation occurs when water is heated, causing the molecules and atoms to move and vibrate so quickly that they lose all attraction and form gas.

Question 20

Define condensation in terms of particle motion.

Answer 20

Condensation occurs when water molecules in the air cool and slow down, gaining attraction and joining together to form liquid water.

Question 21

Describe an everyday example of the particle theory of matter.

Answer 21

An example is how water can transition from a solid (ice) to a liquid (water) and then to a gas (steam) based on temperature changes.

Question 22

How does increased particle motion affect the state of a substance?

Answer 22

Increased particle motion causes the substance to take up more space or expand.

Question 23

What happens to particles during contraction?

Answer 23

During contraction, particles lose thermal energy, move slower, and do not travel as far.

Question 24

Define the particle model of matter.

Answer 24

The particle model is a theory that explains how the particles that make up a substance are arranged, how they move, and how they interact with each other.