Kinetic Model of Matter

Question 1

What are the 3 states of matter?

Answer 1

Solid
Liquid
Gas

Question 2

How are the molecules arranged in a solid and what type of force is between them?

Answer 2

Molecules are arranged in an orderly manner and they are held close together by strong forces of attraction that exist between the molecules

Question 3

How do the molecules in a solid move?

Answer 3

They can only vibrate about a fixed position

Question 4

Is the volume of a solid fixed?

Answer 4

A solid has a fixed volume

Question 5

Can a solid be compressed?

Answer 5

A solid cannot be compressed

Question 6

Does a solid have a fixed shape?

Answer 6

A solid has a fixed shape

Question 7

What happens when we heat a solid?

Answer 7

Its molecules gain kinetic energy and vibrate more and more. The distance between the molecules increase slightly and the solid is said to have expanded

Question 8

How are the molecules arranged in a liquid and what type of force is between them?

Answer 8

The molecules are loosely packed together as they are held by moderate forces of attraction that exist between the molecules

Question 9

How do the molecules in a liquid move?

Answer 9

They can only interchange positions

Question 10

Is the volume of a liquid fixed?

Answer 10

A liquid has a fixed volume

Question 11

Can a liquid be compressed?

Answer 11

A liquid cannot be compressed

Question 12

What shape does a liquid have a fixed shape?

Answer 12

It takes the shape of the container it is in

Question 13

What happens when we heat a liquid?

Answer 13

The molecules gain kinetic energy which allow them to move more vigorously throughout the liquid and the intermolecular spacing increases slightly, it expands

Question 14

How are the molecules arranged in a gas and what type of force is between them?

Answer 14

The molecules are far apart due to the weak forces between them

Question 15

How do the molecules in a gas move?

Answer 15

The molecules move freely and and randomly

Question 16

Is the volume of a gas fixed?

Answer 16

A gas has no fixed volume

Question 17

Can a gas be compressed?

Answer 17

A gas can be compressed

Question 18

Does a gas have a fixed shape?

Answer 18

It has a variable shape

Question 19

What happens when we heat a gas?

Answer 19

The molecules gain kinetic energy and they move very fast, colliding with one another and with the inner walls of the container more violently and at a greater force. This results in an increase in the gas pressure

Question 20

How does gas exert pressure in a container?

Answer 20

The molecules are continuously moving in a random manner and they collide with each other and the inner walls of the container at a certain rate. A pressure is exerted on the surfaces when the molecules are in collision

Question 21

Define evaporation

Answer 21

A process where liquid molecules escape, from the liquid surface, as gas molecules at any temperature

Question 22

How does evaporation cause cooling?

Answer 22

The molecules near the surface have more kinetic energy than the molecules at the bottom of the container. The more energetic molecules have enough energy to overcome the forces of attraction and become a gas. The molecules that don’t have enough energy absorb heat from the surroundings. The average kinetic energy decreases and the temperature of the liquid falls

Question 23

What are 5 factors that affect the rate of evaporation?

Answer 23

1) Temperature
2) Surface area
3) Wind
4) Nature of liquid
5) Pressure

Question 24

How does an increase in temperature increase the rate of evaporation?

Answer 24

The liquid molecules gain kinetic energy and overcome the forces of attraction and they escape as a gas

Question 25

How does a decrease in temperature decrease the rate of evaporation?

Answer 25

There is a loss of kinetic energy and the molecules do not have enough energy to break the forces of attraction between the molecules to become a gas

Question 26

How does a large surface area increase the rate of evaporation?

Answer 26

More molecules are near the liquids surface and they can absorb heat from the surroundings and overcome the forces of attraction to escape from the surface

Question 27

How does a smaller surface area decrease the rate of evaporation?

Answer 27

Fewer molecules are near the surface

Question 28

How does the presence of wind increase the rate of evaporation?

Answer 28

The gas molecules that escape from the surface are carried away with the wind so no saturation of vapour takes place above the liquid surface.

Question 29

How does the absence of wind decrease the rate of evaporation?

Answer 29

Evaporation is obstructed by the gas molecules that escape from the surface of the liquid but they stay above the surface causing saturation of vapour

Question 30

How does a viscous liquid lower evaporation rate?

Answer 30

The forces of attraction between the molecules are stronger and the molecules require more energy to allow the liquid molecules to escape as gas

Question 31

How does a volatile liquid increase the rate of evaporation?

Answer 31

It has weaker forces of attraction between the molecules so it is easy for the molecules to escape and become a gas

Question 32

How does a high pressure lower the rate of evaporation?

Answer 32

Pressure acts on the surface of the liquid and it increases the minimum amount of energy that a molecule needs to escape from the surface

Question 33

How does a low pressure increase the rate of evaporation?

Answer 33

The amount of energy needed for the liquid molecules to escape as gas is lower than normal pressure