Chapter 9 - Kinetic Model of Matter

Question 1

4 Properties of Gas

Answer 1

No fixed shape and volume
Compressible
Low density
Very weak force of attraction between particles

Question 2

4 Properties of Liquid

Answer 2

Fix volume but no fixed shape
Incompressible
High density
Strong intermolecular force of attraction between particles (Weaker than solid)

Question 3

4 Properties of Solid

Answer 3

Fix shape and volume
Incompressible
High density
Strong intermolecular force of attraction between particles

Question 4

Why Solid have fixed shape and volume?

Answer 4

Molecules are closely packed together and held in fixed position by the strong intermolecular force of attraction

Question 5

Why Solid have high density?

Answer 5

Molecules are closely packed together. So there is a large number of particles per unit volume

Question 6

Why Solid is incompressible?

Answer 6

Molecules are closely packed together and there is no space between them

Question 7

Why Liquid have fixed volume but no fixed shape?

Answer 7

Molecules are closely packed together with strong intermolecular force bewteen them. but they are free to move about WITHIN the liquid

Question 8

Why Liquid have relatively high density?

Answer 8

Molecules are closely packed together, slightly further apart than in solid, and there is large number of particles per unit volume, slightly less than in solid.

Question 9

Why Liquid is incompressible?

Answer 9

Molecules are closely packed together, slightly further apart than in solid, and there is little space bewteen them

Question 10

Why gas do not have fixed volume and shape?

Answer 10

Molecules are very far apart and they are free to move around

Question 11

Why gas is compressible

Answer 11

Molecules are very far apart and there is a large empty space between them

Question 12

Why gas have low density?

Answer 12

Molecules are very far apart and there is very little particles per unit volume

Question 13

Describle the set-up for the experiment used to study Brownian Motion

Answer 13

Apparatus used:
Microscope
Glass cover
Light source (Torchlight)
Smoke Particle
Beaker

Microscope on top of the beaker
Beaker filled with smoke particles and covered by glass cover
Light source shine on the beaker

Question 14

What are the two observations of the Brownian Motion experiment and explain why?

Answer 14

The smoke particles appears to be bright spots because the particles reflect light that shine on them.

The smoke particles move in RANDOM and CONTINUOUS motion. (The larger the particle, the less agitated the motion). This is because the smoke particles are larger than the small air particles, they are BOMBARDED continuously and randomly by the air particles

Question 15

What will we observe if the Brownian Motion Experiment is repeated at a higher temperature?

Answer 15

The smoke particles will move much faster and more vigorously

Question 16

Why does a container filled with air does not “collapse” due to the air pressure acting on it from the outside

Answer 16

Air particles in the container exerted a pressure on the inner wall of the container. The air particles are moving constantly and collide with the inner wall of the container, exerting a force on it.

Question 17

When a container filled with gas is heated, the gas exerts a GREATER pressure on the walls of container. Why? Explain in terms of the kinetic theory.

What is the relationship between pressure and temperature? Graph?

Answer 17

When the TEMPERATURE of air molecules increases, the air molecules will move FASTER and thus have greater KINETIC ENERGY. Thus increase the RATE and FORCE of the collision with the walls of the container

Direct Proportional
L / graph

Question 18

A syringe contains some air. Initially, the piston can be pushed through some distance easily. Eventually, greater effort is required to push the piston further. Why?

In this experiment set-up, temperature must kept constant. How do we minimize temperature change in this set-up?

What is the relationship between pressure and volume? Graph?

Answer 18

As the piston is pushed in, the volume of the air decreases, the air particles thus have lesser space to move around. Hence, the rate of collisions increases, resulting in greater force, lead to greater pressure

Move the Piston slowly, so to create lesser fiction, then lesser heat will be generated

Inverse Proportional
L( graph

Question 19

A syringe fill with air is placed vertically upright with a metal ball on the piston. The air in the syringe is heated. Pressure to the air is kept constant. Why there is no change in pressure when the air is heated?

Answer 19

When the air is heated, the air molecules will move faster and gain more kinetic energy. Thus, the rate and force of the collision with the walls of the container increases, exerting a greater pressure. On the other hand, the air expands and move further apart, resulting in greater space. Hence, the rate of collision decreases, exerting a lesser pressure. The increase and decrease of pressure cancel out each other and result in constant pressure.