Can Matter Change Its State?

Question 1

DID YOU LEARN THE ACTIVITY OF MELTING OF ICE AND BOILING OF WATER FROM THE LAB RECORD?

Answer 1

Yes

Question 2

Define melting point.

Answer 2

The minimum temperature at which a solid melts to become a liquid at atmospheric temperature.

Question 3

Explain the process by which solid melts and is converted to a liquid.

Answer 3

On increasing the temperature of solids, the kinetic energy of the particles increases. Due to the increase in kinetic energy, the particles start vibrating with greater speed. The energy supplied by heat overcomes the forces of attraction between the particles. The particles leave their fixed positions and start moving more freely.

Question 4

What is the melting point of a solid the indication of?

Answer 4

A solid’s melting point indicates the strength of the force of attraction between its particles.

Question 5

What is the melting point of ice?

Answer 5

273.15 K

Question 6

What is another name for melting (the change of solid state into liquid state)?

Answer 6

Fusion

Question 7

When a solid melts, its temperature remains the same, so where does the heat energy go?

Answer 7

The heat gets used up in changing the state by overcoming the forces of attraction between the particles. As this heat energy is absorbed by ice without showing any temperature rise, it is considered that it gets hidden in the contents of the beaker.

Question 8

What is the name of the hidden heat used up in melting?

Answer 8

Latent heat of fusion.

Question 9

Define latent heat of fusion.

Answer 9

The amount of heat energy that is required to change 1kg of a solid into liquid at atmospheric pressure at its melting point is known as the latent heat of fusion.

Question 10

Why do particles in water at 273 K have more energy as compared to particles in ice at the same temperature?

Answer 10

Particles in water have more energy than ice at the same temperature because the particles in water have absorbed extra energy in the form of latent heat of fusion.

Question 11

Define boiling point.

Answer 11

The temperature at which a liquid starts boiling at the atmospheric pressure.

Question 12

Boiling is a ______ phenomenon.

Answer 12

Bulk

Question 13

What is the boiling point of water?

Answer 13

373 K

Question 14

How does camphor turn directly from solid to gas when you heat it? What is this process called?

Answer 14

When camphor is heated, a change of state directly from solid to gas without changing into liquid occurs. This process is called sublimation.

Question 15

What is the process of changing from a gaseous state to a solid state called?

Answer 15

Desublimation or deposition.

Question 16

State two things you can do to liquefy gases?

Answer 16

1. Apply more pressure
2. Reduce the temperature

Question 17

Why is solid CO2 stored under high pressure?

Answer 17

Solid CO2 gets converted directly into a gaseous state on the decrease of pressure to 1 atmosphere.

Question 18

We can say that _____ and _____ determine the state of a substance, whether it be solid, liquid or gas.

Answer 18

Pressure, temperature

Question 19

Draw a diagram of the interconversion of the three states of matter.

Answer 19

Solid to Liquid - Fusion
Liquid to Solid - Solidification
Liquid to Gas - Vaporisation
Gas to Liquid - Condensation
Gas to Solid - Deposition
Solid to Gas - Sublimation