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: less closely packed than in solid state in a disorderly manner
• attractive forces betw particles: less strong
• particle movement: slides past one another freely and randomly throughout the liquid
  Compressibility: no

Question 4

Gases

Answer 4

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

Question 5

How temperature is affected by heating/cooling

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

Answer 7

1. Substance absorbs/loses thermal energy from the surroundings which is equal to the energy used to overcome the forces of attraction between the particles/particles lose kinetic energy, moves slower and closer together and becomes less disorderly.
2. The tempt remains constant throughout the () process as the average kinetic energy of the substance remains constant.

Question 8

Particles lose heat Answ formula

Answer 8

When a substance is cooled, particles lose thermal energy which is converted to less kinetic energy. With decreased average kinetic energy, the particles slide past one another throughout the liquid freely/vibrates and rotates about fixed positions slower . Thus temperature of the liquid decreases.

Question 9

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 9

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 10

evaporation vs boiling

Answer 10

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

Similarity:
Both involves a change of state from liquid to gas

Question 11

Sublimation

Answer 11

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 12

Vapour deposition

Answer 12

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

Question 13

Explain why dry ice occupies less space than CO2 gas

Answer 13

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

Question 14

diffusion

Answer 14

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

Question 15

Effect of temperature on rate of diffusion

Answer 15

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

Question 16

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

Answer 16

X has a greater relative molecular mass of () than nitrogen () and hence,x diffuses more slowly and travels a lesser distance

Question 17

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

Answer 17

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 white ring of ammonium chloride is formed nearer to the end of the glass tube concentrated HCl.

Question 18

Diffusion to uniform spread

Answer 18

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 19

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 19

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 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. What happens if the position of the 2 gases are switched?

Answer 20

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

Question 21

The HCl and NH3 experiment is repeated at a lower temperature. (B) Suggest one similarity and one difference between the observations made in experiment A and B.

Answer 21

Similarity: The position where the white ring will be found in the tube will be closer to the cotton wool soaked in concentrated HCl.
Difference: the white ring will take a longer time to form as the rate of diffusion is slower due to the lower temperature.

Question 22

Describe what changes to the diagrams are necessary to show what happened a when a liquid is added to another liquid. (2m)

Answer 22

The particles in the diagram needs to be closer and arranged in a disorderly manner.
There should be 2 layers of liquids with different particles (different densities)

Question 23

Describe what changes to the diagrams are necessary to show what happens when a liquid is added to another liquid.

Answer 23

The liquid particle should be packed more closely together and there should be more particles per unit volume.
One of the liquid will have particles occupying the bottom of the flask, as indicated by the particles at the bottom, while the other liquid will have particles occupying the space above.
There are little changes in the arrangement of particles unlike in the diagram as diffusion occurs more slowly in liquids than gases.

Question 24

Predict and explain the differences in distance the ions have moved in beakers A and B and in A and C after 10 minutes.

Answer 24

The ions in beaker B moved a greater distance than the ions in beaker A. [1] At higher temperature, the ions in B has a greater kinetic energy and hence move faster and travel a further distance. [1]

Ions in beaker C moved a greater distance than ions in A. [1] At the same temperature, V2+ has a smaller relative mass than Cu2+ ions. Thus V2+ ions move faster and travel a further distance. [1]

(CANNOT WRITE ATOMIC MASS SINCE iTS IONS)

Question 25

Explain why the volume increases [2]

Answer 25

HCl molecules gain kinetic energy and moves faster and spread further away from each other. Space between molecules increases, increasing the volume.