particle model of matter

Question 1

what is the definition of density

Answer 1

the mass per unit volume of material

Question 2

state the different states of matter in order (Least to most) of density of atoms

Answer 2

least dense: gas
middle: liquid
most dense: solid

Question 3

describe the particle arrangement of a solid

Answer 3

tightly packed in a regular arrangement
particles can only vibrate on the spot

Question 4

describe the particle arrangement of a liquid

Answer 4

close together
but with an irregular arrangement
they can flow over each other

Question 5

describe the particle arrangement of a gas

Answer 5

separated, with no regular movement
particles can move freely

Question 6

what is always conserved when a substance undergoes a change of state

Answer 6

mass

Question 7

how does a chance of state differ from a chemical change

Answer 7

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

Question 8

what is sublimation

Answer 8

when a solid changes into a gas without passing through a liquid state

Question 9

what is evaporation

Answer 9

when a liquid changes into a gas state

Question 10

what is the opposite of evaporation

Answer 10

condensation

Question 11

what is the internal energy of a substance

Answer 11

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

Question 12

how does heating affect the energy of a substance

Answer 12

heating transfers energy to the substance
it increases the energy of the particles that make up the substance

Question 13

what 2 things can heating a substance do

Answer 13

1. raise the temp
2. change the state of the substance

Question 14

what 3 factors determine the temp change of a system

Answer 14

1. mass of substance being heated
2. type of material
3. energy inputted into the system

Question 15

define specific heat capacity

Answer 15

the amount of energy needed to increase the temp of 1kg of a substance by 1 degrees

Question 16

describe how the internal energy and temperature of a substance Changs when a change of state occurs

Answer 16

the internal energy of the substance will be increased or decreased
the temperature of the substance will remain constant

Question 17

define specific latent heat

Answer 17

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

Question 18

state the equation for the energy required to change state

Answer 18

energy to change state = mass x specific latent heat

Question 19

what is specific latent heat of fusion?

Answer 19

the energy required to change 1kg of a substance from solid state to liquid state without a change in temperature

Question 20

what is the specific latent heat of vaporisation

Answer 20

the energy required to change 1kg of a substance from a liquid state to a gas state (vapour) without a change in temperature

Question 21

describe the motion of molecules in a gas

Answer 21

they are in a constant random motion

Question 22

what factors affects the average kinetic energy of gas molecules

Answer 22

the temperature of the substance
the higher the temperature the higher the average kinetic energy of the molecules

Question 23

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

Answer 23

pressure of the gas will increase as temperature increases

Question 24

why does pressure increase as temperature increases (constant volume)

Answer 24

kinetic energy of molecules increase
collisions between molecules becomes more frequent
greater rate of change of momentum
greater force and therefore pressure

Question 25

describe the force that the pressure of a gas exerts on the walls of its container

Answer 25

the net force at right angles to the containers surface
the force increases as pressure increases

Question 26

explain how increasing the volume of a gas results in a decrease of pressure

Answer 26

• molecules become more spread out and so time between collisions increase
• this reduces rate of collisions
• rate of change of momentum decreases, and so force exerted on container decreases, resulting in a lower pressure

Question 27

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

Answer 27

being constant

Question 28

what is the unit used for pressure

Answer 28

pascal

Question 29

what increases when you do work on a gas?

Answer 29

• the internal energy of the gad
• this can also lead to an increase of temperature

Question 30

why does the temp of air inside a bike pump increase when it is pumped?

Answer 30

• work is done on a gas when it is compressed
• doing work on a gas increases its internal energy, so also increases the average kinetic energy of the molecules
• temp increases with an increase of average kinetic energy