Chapter 1: States of Matter

Question 1

Explain (and use) the term: MELT

Answer 1

When a solid is heated, its particles get more energy and vibrate more. This makes the solid expand. At the melting point, the particles vibrate so much that they break away from their positions. The solid turns liquid.

Question 2

Explain (and use) the term: BOIL

Answer 2

When a liquid is heated, the particles get more energy and move faster. They bump into each other and bounce further apart, making the liquid expand. They break away and form a gas.

Question 3

Explain (and use) the term: EVAPORATE

Answer 3

Some particles in a liquid have more energy than others, so they are able to break away and form a gas. (This is why puddles of rain dry up in the sun)

Question 4

Explain (and use) the term: CONDENSE

Answer 4

Condensing is the opposite of evaporation. When a gas is cooled down, it loses energy and move slower. When they end up colliding, they do not have enough energy to bounce away, so they stay together and form a liquid.

Question 5

Explain (and use) the term: MELTING POINT

Answer 5

The temperature in which the substance changes states from a solid to a liquid.

Question 6

Explain (and use) the term: BOILING POINT

Answer 6

The temperature in which a substance changes states from a liquid to a gas

Question 7

Explain (and use) the term: FREEZING POINT

Answer 7

The temperature in which a substance changes state from a liquid to a solid

Question 8

Give two examples of evidence, from the lab, that matter is made of particles

Answer 8

1: Potassium Manganate (VII) crystal in a beaker of water. The crystal will dissolve, and the particles will slowly diffuse with the water particles. The two processes that take place are diffusion and dispersion (the action or process of distributing things over a wide area)
2: Two open gas jars with their open ends on each other to form a closed tube with a few drops of red-brown bromine at the bottom. The colour spreads upwards as the particles diffuse with the air particles.

(see doc c1 f8 for diagrams)

Question 9

Explain what diffusion is and how it happens

Answer 9

Diffusion is the movement of particles from a region of high concentration to a region of low concentration. It happens when different particles collide with one another and bounce off in all directions

Question 10

Name the 3 states of matter and give their physical properties. Draw particle arrangements for each state.

Answer 10

Solid: hard, fixed shape and volume, does not flow
Liquid: flows easily, fixed volume but shape changes. Takes the shape of container.
Gas: does not have fixed volume or shape. Spreads out to fill container, much lighter than the same volume of solid or liquid

(see doc c1 f10 for particle arrangements)

Question 11

Describe how a substance changes state when you heat it, and explain this using the idea of particles

Answer 11

When you heat a substance, the particles will move faster and break away from the strong bonds between them. A solid will turn into a liquid at the substance’s melting point, and then at its boiling point, the liquid will turn into a gas

Question 12

Sketch and label a heating and cooling curve

Answer 12

(see doc c1 f12 for diagrams)

Question 13

Explain why gas exerts a pressure

Answer 13

When the particles in a gas collide with one another and bounce off the walls of a container, it exerts pressure on it.

Question 14

Explain why the pressure increases when you heat a gas.

Answer 14

When you heat a gas, the particles gain energy and bounce around faster. They hit the walls of the container with more force, therefore increasing the pressure

Question 15

Explain why the pressure increases when you push gas into a smaller space.

Answer 15

When you compress gas, the particles have less room to move and will collide with each other more frequently.

Question 16

Describe an experiment to show that a gas will diffuse faster than another gas that has heavier particles

Answer 16

The particles in hydrogen chloride gas are twice as heavy than the particles in ammonia gas, therefore ammonia gas will diffuse faster than hydrogen chloride gas. This is evident in the experiment because the white smoke that forms where they meet is closer to the cotton wool soaked in hydrogen chloride gas, meaning it did not travel as far as the ammonia gas particles.

(see doc c1 f16 for diagrams)

Question 17

Explain how and why the temperature affects the rate at which a gas diffuses

Answer 17

When the temperature is higher, the particles have more energy and collide with each other more, therefore incorporating themselves with the other particles faster.