PNM

Question 1

state the Kinetic Theory of Matter

Answer 1

all matter is made up of numerous tiny particles in continuous random motion

Question 2

what is Brownian motion?

Answer 2

the random movement of particles suspended in a liquid or gas

Question 3

state the shape, volume, ease of flow and compressibility of solids

Answer 3

solids:
- have fixed shape
- have fixed volume
- do not flow
- are not compressible

Question 4

state the shape, volume, ease of flow and compressibility of liquids

Answer 4

liquids:
- have no fixed shape, they take the shape of the container
- have fixed volume
- can flow
- are not compressible

Question 5

state the shape, volume, ease of flow and compressibility of gases

Answer 5

gases:
- have no fixed shape, they take the shape of the container
- have no fixed volume
- can flow
- are compressible

Question 6

draw 2D particle diagrams for a solid, liquid and gas

Answer 6

solid: min. 9 particles, regular pattern, should fill up entire box (touch all sides of box), should touch each other
liquid: min. 9 particles, no regular pattern, some particles must touch boundaries of box, should touch each other
gas: min. 5 particles, no regular pattern, particles can be separate from each other, do not have to touch boundaries of box
note: all particles must be the same size.

Question 7

state the arrangement of particles, motion of particles, and forces of attraction between particles in a solid

Answer 7

arrangement: particles arranged in a fixed, regular pattern, packed closely together.
motion: particles vibrate about fixed positions.
forces of attraction: strong forces of attraction between particles.

Question 8

state the arrangement of particles, motion of particles, and forces of attraction between particles in a liquid

Answer 8

arrangement: particles are free to move. no fixed positions, no regular pattern. particles further apart than in a solid, closer together than in a gas.
motion: particles slide freely past one another and can change positions.
forces of attraction: weaker forces of attraction than in solid, stronger than in gas.

Question 9

state the arrangement of particles, motion of particles, and forces of attraction between particles in a gas

Answer 9

arrangement: particles are free to move. no fixed positions, no regular pattern. particles very far apart.
motion: particles move freely and randomly at high speeds, occupying any available space.
forces of attraction: negligible/very weak forces of attraction between particles.

Question 10

what influences the shape & volume of a substance, as well as whether it can flow?

hint: based on Kinetic Theory of Matter

Answer 10

motion of particles

Question 11

what influences the compressibility and density of a substance?

hint: based on Kinetic Theory of Matter

Answer 11

distance/arrangement of particles

Question 12

why do solids have a fixed shape while liquids and gases do not?

hint: answer based on Kinetic Theory of Matter

Answer 12

particles in a solid can only vibrate about fixed positions while particles in a liquid can slide freely past one another and change positions, and particles in a gas move freely and randomly at high speeds to occupy any available space

Question 13

why can gases be compressed while solids and liquids cannot?

hint: answer with Kinetic Theory of Matter

Answer 13

the particles in a gas are very far apart and occupy any available space, while the particles in a solid are packed closely together, and the particles of a liquid are further apart than in a solid, but closer together than in a gas

Question 13

in the heating curve of pure water:

describe what happens to particles before and during melting

Answer 13

before melting: as thermal energy is absorbed by particles, they vibrate more vigorously about fixed positions and temperature increases.
during melting: at the melting point, even though thermal energy is still being absorbed by the particles, temperature remains constant. this is because all the thermal energy is used to overcome forces of attraction between the particles until the ice completely melts.

Question 14

in the heating curve of pure water:

describe what happens to particles before and during boiling

Answer 14

before boiling: as thermal energy is being absorbed by particles, they slide freely past one another at higher speeds and temperature increases.
during boiling: at the boiling point, even though thermal energy is still being absorbed by particles, temperature remains constant. this is because all the thermal energy is used to overcome forces of attraction in the liquid until it completely boils.

Question 15

in the cooling curve of pure water:

describe what happens to particles before and during condensation

Answer 15

before condensation: as thermal energy is lost by particles, they move freely and randomly at decreasing average speeds, and thus temperature decreases
during condensation: at the condensation point, temperature remains constant even though thermal energy is still being lost to the surroundings. this is because as forces of attraction between particles in a gas increase, particles come closer together and heat is released. all the thermal energy released by the substance is lost to the surroundings, thus temperature remains constant.

Question 16

in the cooling curve of pure water:

describe what happens to particles before, during and after freezing

Answer 16

• before freezing: as thermal energy is lost before the freezing point is reached, particles slide past one another freely at slower average speeds, thus temperature decreases.
• during freezing:at the freezing point, even though thermal energy is still being lost to the surroundings, temperature remains constant.
• as the forces of attraction between particles increase, particles are drawn into a fixed, closely packed state, and heat is released.
• all the thermal energy released by the substance is lost to the surroundings and hence temperature remains constant.
• after freezing: as thermal energy is lost by the substance, particles vibrate about their fixed positions at slower average speeds, causing temperature to decrease

Question 17

using Kinetic Theory of Matter, explain how expansion of a metal ball occurs upon heating

Answer 17

as the ball is heated, the particles in the ball gain more energy and vibrate more vigorously about their fixed positions, so the distance between particles increases, and thus the volume of the ball increases, leading to the ball expanding.

Question 18

using Kinetic Theory of Matter, explain how the contraction of a metal ball occurs upon cooling

Answer 18

as the ball is cooled, particles in the ball lose energy and vibrate less vigorously about their fixed positions, so the distance between particles increases, and the volume of the ball thus decreases, leading to the ball contracting.