P3 - Particle Model of Matter

Question 1

All matter is made up of what?

Answer 1

Particles

Question 2

Describe the particle arrangement of:

a) Solids
b) Liquids
c) Gases

Answer 2

a) Strong forces of attraction, hold particles close together in a fixed, close arrangement. They don’t have much have much energy so they can only vibrate around a fixed point
b) Weaker forces of attraction, particles are close together but can move past each other and form irregular arrangements. More energy than particles in a solid - they move in random directions at low speeds
c) Almost no forces of attraction, have more energy than liquids & solids - free to move, and constantly moving with random directions and speeds

Question 3

Colliding gas particles creates what?

Answer 3

Pressure
Particles in gases are free to move around. As they move, they collide with each other and whatever else happens to get in the way (like sides of container kept in). When they collide, they exert a force on it. Pressure is the force exerted per unit area. So in a sealed container, the outward gas pressure is the total force exerted by all of the particles in the gas on a unit area of the container walls

Question 4

Increasing the temperature of a gas can increase it’s what?

Answer 4

Pressure - temperature transfers energy to kinetic energy stores. The temperature of a gas is related to the average energy in the kinetic energy stores of the particles of the gas. Higher temperature = higher average energy
So as you increase the temperature of a gas, the average speed of its particles increases. This is because the energy in the particles’ kinetic energy stores is 0.5mvsquared. This means that for a gas at a constant volume, increases it’s temperature increases its pressure, as it hits surfaces more often and faster

Question 5

Complete the blanks:
Increasing temperature of a gas increases pressure, as the particles are travelling ______, it means that they hit the sides of the container ____ often in a given amount of ____. Each particle also has a larger _______, which means that they exert a larger force when they collide with the container. These factors both _______ the total force exerted on a unit area, and so increases the pressure

Answer 5

Quicker
More
Time
Momentum
Increase

Question 6

What is the formula for density?

Answer 6

Mass/ volume - units for density = kg/m cubed or g/cm cubed

1 g/cm cubed = 1000 kg/m cubed

Question 7

What is the formula volume?

Answer 7

Mass/ volume

Question 8

In terms of density and volume, what is the formula for mass?

Answer 8

mass= density x volume

Question 9

What is density?

Answer 9

The “compactness” of a substance. It is mass/ volume, with the units kg/m cubed, or in g/cm cubed
1 g/cm cubed = 1000 kg/m cubed

Question 10

The density of an object depends on what?

Answer 10

What it’s made of, and how the particles are arranged.
A dense material has tightly packed together particles.
A less dense material is more spread out
If you compressed the material, its particles would move closer together, and would make it more dense (this wouldn’t change the mass, but decrease the volume

Question 11

Describe the density between the different states of matter

Answer 11

1) Solids are denser than
2) Liquids, which are denser than
3) Gases, the least dense
Because denseness is about how the particles are arranged, more compact is more dense (as can fit more in, increasing mass)

Question 12

Give the practical of measuring the density of a solid object

Answer 12

1) Use a top pan balance to 2 decimal places (more accurate) to measure mass
2a) If it’s a regular solid (like a cube), find the volume by measuring it’s length, width and height with a ruler. Then calculate the volume with the relevant formula for that shape
2b) If it’s an irregular shape, you can submerge it into a eureka can filled with water. The water displaced from the spout (caught in a measuring cylinder) is the volume of the object
3) Use the formula density = mass/ volume to find the density of the object

Question 13

Give the practical to find the density of a liquid

Answer 13

1) Place a measuring cylinder on a top pan balance to 2 decimal places (more accurate) and 0 the balance.
2) Pour 10ml of the liquid into the measuring cylinder, and record the liquid’s mass
3) Pour another 10ml of the liquid into the measuring cylinder, repeating the process until the measuring cylinder is full, recording the total volume and mass each time
4) For each measurement, use the formula to find the density (mass/ volume) Remember that 1 ml = 1 cm cubed
5) Finally take the average of the calculated densities. This gives a value for the density of the liquid

Question 14

What is a eureka can?

Answer 14

A piece of equipment that has a spout near the top going downwards. This means it can only be filled to a certain level

Question 15

What is the formula for specific heat capacity? (It is given in the paper, but still)

Answer 15

Change in thermal energy / (mass x temperature change)

Question 16

What is internal energy?

Answer 16

It is the energy stored in particles that make up a system

The internal energy of a system is the total energy that its particles have in their kinetic and potential energy stores

Question 17

Particles have energy in their kinetic energy stores. What does this cause to particles in a system?

Answer 17

The particles in a system vibrate or move around

Question 18

Why do particles in a system have energy in their potential energy stores?

Answer 18

Because of their position

Question 19

Where is the energy stored in a system?

Answer 19

In its particles (atoms and molecules)

Question 20

Internal energy of a system is the total energy that its particles have. True or false?

Answer 20

False - it is the total energy particles have in their kinetic and potential energy stores

Question 21

What can increase the internal energy of a system and how? What does this lead to?

Answer 21

Heating the system transfers energy to its particles (they gain energy in their kinetic and potential energy stores
Heating the system transfers energy to its particles (they gain energy in their kinetic stores and move faster), increasing the internal energy

This leads to a change in temperature and a change in temperature or a change in state. If the temperature changes, the size of the change depends on the mass of the substance, what it’s made of (the specific heat capacity) ad the energy input.

Question 22

When will a change in state occur?

Answer 22

When a substance is heated enough - the particles will have enough energy in their kinetic energy stores to break the bonds holding them together

Question 23

How do particles change state? (adding heat)

Answer 23

Adding heat will give the particles enough energy in their kinetic energy stores to break the bonds holding them together. WOO!

Question 24

A change of state will lose mass. True or false?

Answer 24

False - a change in state will - like EVERYTHING ELSE - conserve mass. However, if the change in state becomes a gas, it will be difficult to weigh as it is lost to the air, as it seems like mass is lost. Similarly, when cooling something down to a liquid for example, some extra gas may be condensed too, causing an increase in mass, but mass is still conserved
The number of particles doesn’t change, they’re just arranged differently, so mass must be conserved

Question 25

Name the changes in state:

a) Solid –> liquid
b) Liquid –> gas
c) Solid –> gas

d) Gas –> liquid
e) Liquid –> solid
f) Gas –> solid

Answer 25

a) Melting + heat
b) Boiling/ evaporating +heat
c) Sublimating + heat

d) Condensing - heat
e) Freezing - heat
f) Deposition (don’t need to know it, but cool anyway)

Question 26

This is a physical change (rather than a chemical change). This means don’t end up with a new substance - it’s the same substance you started with, just in different form
What am I describing?

Answer 26

A change in state

LIKE YOU SHOULD CHANGE YOUR STATE OF MIND TO BE MORE POSITIVE YEAH

Question 27

What happens if you reverse the change of state (e.g. freeze a substance that has just been melted), what happens to the substance?

Answer 27

It returns to its original form

Question 28

a) Melting + heat
b) Boiling/ evaporating +heat
c) Sublimating + heat

d) Condensing - heat
e) Freezing - heat
f) Deposition (don’t need to know it, but cool anyway)

Answer 28

a) Solid –> liquid
b) Liquid –> gas
c) Solid –> gas

d) Gas –> liquid
e) Liquid –> solid
f) Gas –> solid

Question 29

What is specific latent heat?

Answer 29

The amount of energy needed to change 1 kg of it to on state or another (without changing its temperature says in book, but that doesn’t make sense)

Question 30

Give the difference between specific heat capacity, and specific latent heat

Answer 30

Specific heat capacity is the amount of energy needed to heat 1kg of a material by 1 degree C
Specific latent heat is the amount of energy needed to change 1kg of a material to another state

Question 31

Why are there straight lines on a graph showing temperature against time (x axis)? Graph kinda goes:
. . . . . ____
___/
/

Answer 31

Show that it has changed state. There are flat spots on the heating graph where energy is being transferred by heating but not being used to change the temperature
The energy needed for a substance to change state is called specific latent heat

Question 32

Fill the blanks:
When a substance is melting or boiling, you’re still putting ______ in and so increasing the internal energy, but the energy is used for ________ _____________ bonds rather than raising the temperature. That’s what flat spots on a temp against time (x axis) graph are for - showing where energy is being ___________ by heating but not being used to ______ ___ __________

Answer 32

Energy
Breaking intermolecular
Transferred
Change the temperature

Question 33

Fill the blanks:
When a substance is condensing or freezing, bonds are _______ between particles, which releases ______. This means the internal energy ________, but the temperature doesn’t go down until all the substance has changed state. The ____ parts of a temp against time (x axis) graph are for - showing where energy is being ___________

Answer 33

Forming
Energy
Decreases
Flat
Transferred

Question 34

The energy needed to change the state of a substance is called what?

Answer 34

Specific latent heat

Question 35

For cooling, specific latent heat is the energy what?

Answer 35

Released by a change in state

Question 36

Specific latent heat is different between different materials, and for changing between states. True or false?

Answer 36

True

Question 37

What is the specific latent heat for changing between a solid and a liquid?

Answer 37

(Melting or freezing) is called the specific latent heat of fusion.
The specific latent heat for changing between a liquid and a gas (evaporating, boiling or condensing) is called specific latent heat of vapourisation

Question 38

What is

a) Specific latent heat of fusion?
b) Specific latent heat if vaporisation?

Answer 38

a) the specific latent heat for changing between a solid and a liquid (melting or freezing)
b) The specific latent heat for changing between a liquid and a gas (evaporating, boiling or condensing)

Question 39

What is The specific latent heat for changing between a liquid and a gas?

Answer 39

(Evaporating, boiling or condensing) The specific latent heat of vaporising
The specific latent heat for changing between a solid and a liquid (melting or freezing) is called specific latent heat of fusion

Question 40

Give the formula for specific latent heat

Answer 40

Energy (E) = Mass (m) x Specific Latent heat

J(oules) = kg x J/kg

Question 41

What are the units for specific latent heat?

Answer 41

J/kg, as it’s energy/ mass