Topic 14: Particle Model

Question 1

What is the definition of density?

Answer 1

The mass per unit volume of a material
Density = mass / volume

Question 2

What does state of matter mean?

Answer 2

A form in which matter can exist, based on the particle arrangement in a substance

Question 3

What are the different states of matter in order of density of atoms?

Answer 3

Gas, liquid and solid

Question 4

What is the structure of liquids?

Answer 4

The particles have some kinetic energy, they are free to move and can move around in random directions at very slow speeds

Question 5

What is the movement of particles in a solid?

Answer 5

The particles vibrate around a fixed position as they don’t have enough kinetic energy to move free,y

Question 6

What is the structure of particles in a gas?

Answer 6

Particles in gas have almost no forces between them therefore they are completely free to move and move at high speeds in random directions

Question 7

What is always conserved when a substance undergoes a change of state?

Answer 7

Mass

Question 8

How does a change of state differ from a chemical change?

Answer 8

In a change of state, the material can return to having its previous properties if the change is reversed

Question 9

What is the internal energy of a substance?

Answer 9

The energy stored by the particles and the sum of the total kinetic and potential energies that make up the system

Question 10

What two things can heating a substance do?

Answer 10

Raise its temperature and change the state of the substance

Question 11

What three factors determine the temperature change of a system?

Answer 11

Mass of substance being heated, type of material and energy inputted into the system

Question 12

What is sublimation?

Answer 12

When a solid turns directly into a gas

Question 13

What is the difference between physical and chemical changes in substances?

Answer 13

Physical changes can be reversed and chemical changes cannot be easily reversed

Question 14

How does heating cause a substance to change state?

Answer 14

Heating matter gives particles more potential energy, this energy is used to break the bonds of attraction leading to a change of star

Question 15

Why does heating increase the temperature of substances?

Answer 15

It increases the amount of thermal energy in that substance, it also gives the particles more KE meaning they move faster and their temperature increases

Question 16

What equation could be used to carbon the energy change when a substance is heated?

Answer 16

Energy = mass x specific heat capacity x temperature

Question 17

What is specific heat capacity?

Answer 17

The amount of energy needed to increases the temperature of 1kg of a substance by 1C

Question 18

What does specific latent heat mean?

Answer 18

The amount of energy needed to change the state of 1kg of substance with no change in temperature

Question 19

What equation is for energy required to change state?

Answer 19

Energy = mass x specific latent heat

Question 20

What is the structure of particles in a gas?

Answer 20

Particles in a gas have almost no forces between them therefore they are completely fre to move and move at high speeds in random directions

Question 21

What is the pressure of a gas in terms of the motion of particles?

Answer 21

The particles move in random directions, when they collide with the walls of a container they exert a force which acts at a right angle to the container and this causes pressure

Question 22

What is the equation to calculate pressure?

Answer 22

Pressure = force / area

Question 23

What factor affects the average KE of gas molecules?

Answer 23

Temperature of the gas and the higher the temperature the higher the average KE of the molecules

Question 24

What effect does increasing temperature have on the pressure of a gas when held at constant volume?

Answer 24

Gas pressure will increase as the temperature increases

Question 25

Why does pressure increase as temperature increases?

Answer 25

KE of molecules increases, collisions between molecules becomes more frequent, greater rate of change of momentum and greater force and therefore pressure

Question 26

What is the force that the pressure of a gas exerts on the walls of its container?

Answer 26

The net force acts at right angles to each surface of the container and the force increases as pressure increases

Question 27

How does increasing the volume of gas results in a decrease of pressure?

Answer 27

Molecules become more spread out so rate of collisions decreases and rate of change of momentum decreases, and so force exerted on container decreases resulting in a lower pressure

Question 28

What can be said about the product of pressure and volume for a fixed mass of gas at a constant temperature?

Answer 28

It’s constant

Question 29

What is the unit used for pressure?

Answer 29

Pascal

Question 30

What increases when you do work on a gas?

Answer 30

The internal energy of the gas and this can also lead to an increase of temperature

Question 31

How do you convert between degree Celsius and Kelvin?

Answer 31

Degrees Celsius -> +273 -> Kelvin

Question 32

What is absolute zero?

Answer 32

-273C, particles have no KE and don’t move

Question 33

What equation can be used to calculate the pressure/volume for a gas which the mass is fixed and temperature is constant?

Answer 33

P1 x V1 = P2 x V2

Question 34

Why does the temperature of air inside a bike pump increase when it is pumped?

Answer 34

Work is done on a gas when it’s compressed, doing work on a gas increases it’s internal energy so increases the average KE of the molecules and temperature increases with an increase of average KE