Kinetic Model Of Matter

Question 1

What’re the properties of a solid?

Answer 1

1) Fixed shape
2) Fixed volume
3) Does not flow
4) Highly incompressible

Question 2

What’re the properties of a liquid?

Answer 2

1) No fixed shape/Takes shape of container
2) Fixed volume
3) Flows easily
4) Not compressible

Question 3

What’re the properties of a gas?

Answer 3

1) No fixed shape
2) No fixed volume
3) Assumes shape and volume of its container
4) Highly compressible
5) Flows easily

Question 4

What’s the arrangement of particles in a solid?

Answer 4

Arranged close together in regular pattern.

Question 5

What’s the arrangement of particles in a liquid?

Answer 5

Molecules not arranged in regular pattern and are slightly further apart than in solids.

Question 6

What’s the arrangement of particles in a gas?

Answer 6

Molecules are far apart

Question 7

Explain why solids cannot be compressed.

Answer 7

Molecules are arranged close together and there’s little space between them.

Question 8

Explain why liquids can’t be compressed.

Answer 8

Molecules are close together and there’s little space between them.

Question 9

Explain why gases can be compressed.

Answer 9

Molecules are sparse and there’s lots of space between them.

Question 10

What’re the motion of solid particles?

Answer 10

Balanced forces between molecules which hold them in fixed positions. Molecules vibrate about fixed positions, alternately attracting and repelling one another.

Question 11

What’re the motion of liquid particles?

Answer 11

Molecules vibrate to and fro, alternately attracting and repelling one another with forces which can be just as strong as those in a solid.

Question 12

What’re the motion of gas particles?

Answer 12

Molecules move randomly at high speed, colliding with one another and with walls of container.

Question 13

Explain why solid has a fixed shape and fixed volume.

Answer 13

Strong attractive forces prevent molecules from leaving their positions while repulsive forces which act when they are too close to each other prevent them from collapsing.

Question 14

Explain why liquids flow and take the shape of their container.

Answer 14

Though there’s forces between molecules, they are not held in fixed position. Because of this, molecules move among one another throughout liquid.

Question 15

Explain why gases are able to fill a container completely and freely.

Answer 15

Intermolecular forces act only at moments of collision. Otherwise, molecules are so far apart that the intermolecular forces become negligible.

Question 16

Explain why a solid is able to expand.

Answer 16

When solid heated, molecules gain energy and vibrate. Separation between molecules increases slightly and solid expands.

Question 17

Explain why liquids have definite volumes.

Answer 17

Attractive forces between molecules make it difficult for molecules to leave liquid.

Question 18

How do liquids expand?

Answer 18

When liquid heated, molecules vibrate and move about vigorously. Thus liquid expands slightly only to a very slight extent.

Question 19

Explain the Brownian motion.

Answer 19

Continuos haphazard motion of particles, such as, that of smoke particles in smoke cell. Random motion of smoke particles due to unbalanced forces acting on smoke particles when air molecules collide with them. Irregular/random motion of smoke particles result of smoke particles being bit by unseen fast moving air molecules.

Question 20

What is the kinetic theory of matter?

Answer 20

It states that all matter made of large number of tiny atoms/ molecules which are in continuous motion.

Question 21

Explain why Brownian motion of smoke particles in the air becomes more vigorous when temperature is higher.

Answer 21

Surrounding air particles move faster, hitting smoke particles more frequently with greater force. When temperature increases, thermal energy transferred to molecules and molecules gain KE, causing molecules to move faster.

Question 22

Explain the motion of molecules and pressure.

Answer 22

Pressure of gas due to elastic collisions of gas molecules with walls of container. Gas molecules collide with container’s walls, force exerted on wall. Magnitude of force increases when: speed of molecules increase, more molecules collide with wall per unit time.

Question 23

Why does pressure increase as temperature increase?

Answer 23

For fixed mass of gas at constant volume, when temperature of gas in container increases, molecules move faster and hit walls with greater frequency and force, causing pressure to increase.

Question 24

Why does volume of gas increase when temperature increase?

Answer 24

Kinetic energy of gas molecules increases, collisions of air molecules increase, thus volume increases as pressure is kept constant.

Question 25

Why does the pressure of a gas in a container increase when volume decreases?

Answer 25

1. Area of walls of container is smaller
2. Number of gas molecules per hit volume increases.
3. Hence rate of collision of gas molecules with unit area of container’s walls increases.

Question 26

Explain the motion of molecules and temperature.

Answer 26

As temperature increases, surrounding air particles hit walls with greater force and higher frequency. When temperature increases, thermal energy is transferred to molecules, molecules gain KE and move faster