2 — KTM

Question 1

Kinetic particle theory

Answer 1

KTM state that all matter is made up of tiny particles and these particles r in constant and random motion

Question 2

Solids

Answer 2

• Particle arrangement: very closely packed in an orderly manner
• Attractive forces between particles: very strong
• Particle movement: vibrate and rotate about fixed positions
• compressibility: no

Question 3

Liquids

Answer 3

• Particle arrangement: closely packed in a disorderly manner
• attractive forces betw particles: less strong
• particle movement: slides past one another freely throughout the liquid
  Compressibility: no

Question 4

Gases

Answer 4

• Particle arrangement: very far apart in a disorderly manner
• Attractive forces between particles: very weak
• Particle movement: move quickly and randomly in any direction
• compressibility: yes

Question 5

Changes of state

Answer 5

Substance heated/cooled -> thermal energy is transferred to/from the substance/(to its surroundings) -> kinetic energy increases/decreases -> increase/drop in tempt.

Question 6

Particles gain heat Answ formula

Answer 6

Thermal energy is converted to kinetic energy of the particles. Particles vibrate and rotate faster about their fixed positions/slides past one another in the liquid freely with increasing speed -> tempt of the (S/L) substance increases.

Question 7

Particles change of state (melting/boiling)

Answer 7

1. Thermal energy is absorbed from the surroundings and the tempt of the S/L is at its melting/boiling point.
2. Particles with increased energy can overcome the forces of attraction in the S/L state.
3. S: The orderly packing arrangement of the particles is disrupted/
   /L: the particles move further apart, quickly and randomly.
4. Both S and L/L and G are present during the melting/boiling process.
5. The tempt remains constant throughout the melting process until all the substance has melted.

Question 8

Particles lose heat Answ formula

Answer 8

Kinetic energy of the particles is converted to thermal energy which is transferred to the surroundings. With less kinetic energy, the particles slow down. Temperature of the liquid decreases.

Question 9

Particles change of state (freezing/condensation)

Answer 9

1. Particles lose energy to the surroundings until it reaches the freezing/condensation point
2. Particles with less energy are drawn closer together by the forces of attraction between them
3. The particle arrangement becomes more orderly/less disorderly
4. Both S and L/L and G are present during freezing
5. The temperature remains constant throughout the freezing process until all the liquid has solidified.

Question 10

Water contracts until temperature decreases to approximately 4d.C. Going lower than that, it expands slightly until it reaches freezing point. When water freezes, it expands by approximately 9%! Why does ice floats on water? Reason:

Answer 10

This is due to the structure of water molecule. The arrangement of water molecules below 4d.c. Results in it having a larger volume. Thus, ice is less dense than water and floats on it.

Question 11

Differences between evaporation and boiling

Answer 11

1. E occurs at below boiling point but B only occurs at boiling point
2. E occurs only at the surface of the liquid but B occurs throughout the liquid
3. E occurs slowly but B occurs rapidly

Question 12

Sublimation

Answer 12

Thermal energy from surroundings is transferred to the solid -> substance converts from S to G -> tempt remains constant until all the substance is in gaseous state -> sublimation

Question 13

Vapour deposition

Answer 13

Thermal energy transferred from gas to surroundings -> particles in gas r cooled until they slow down and arrange themselves into the solid state

Question 14

Explain why dry ice occupies less space than CO2 gas

Answer 14

Dry ice particles are more closely packed together than particles in CO2 gas, hence, has a smaller volume, occupying less space.

Question 15

diffusion

Answer 15

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration.

Question 16

Effect of temperature on rate of diffusion

Answer 16

Particles have more kinetic energy at higher temperatures. Hence, particles in liquid and gases move more quickly compared to particles in solids.

Question 17

Effect of particle mass on rate of diffusion (only liquids and gases)

Answer 17

X has a greater relative molecular mass than nitrogen and hence,x diffuses more slowly.

Question 18

HCl and aq NH3 demonstration of effect of particle mass on diffusion

Answer 18

NH3 gas particles have a lower relative molecular mass (Mr= 17) than HCl gas (Mr = 36.5). Thus, NH3 particles diffuse faster and travel further than HCl gas. Therefore, the product, white ring of ammonium chloride is formed nearer to the end of the glass tube concentrated HCl.

Question 19

Diffusion application

Answer 19

X diffuses down from A, a region of higher concentration to B, a region of lower concentration. Concentration of x becomes the same throughout the cup eventually.

Question 20

A set-up involving colourless H2 (g) and brown NO2 (g) is shown. Mass of a particle of NO2 is 23x the mass of a particle of H2. H2 is above, NO2 is below and both r separated by a glass cover. Describe what happens when the glass cover is removed.

Answer 20

Gases will move from their respective gas jars to the other gas jar as diffusion of the gases occur from a region of higher concentration to a a region of lower concentration. Eventually, the gas jar will have brown colour spread uniformly throughout both gas jar.

Question 21

A set-up involving colourless H2 (g) and brown NO2 (g) is shown. Mass of a particle of NO2 is 23x the mass of a particle of H2. H2 is above, NO2 is below and both r separated by a glass cover. What happens is the position of the 2 gases are switched?

Answer 21

The diffusion process will take place faster as gravity will cause the higher density NO2 gas to move to the lower gas jar faster.