particle model of matter

Question 1

what are the three states of matter

Answer 1

solid,liquid and gas

Question 2

what are particles like in solids

Answer 2

• string forces of attraction hold the particles together in a fixed regular arrangement
• particles dont have much energy so can only vibrate ina fixed postions
• the density is usally the highest in this state as they are the closest together

Question 3

what are the particles like in liquids

Answer 3

-weaker forces of attraction
- particles are close together but can move past each other and form irregular arrangements
- the particles wll have more energy than solids but less than gas
- tehy move in reandom directions at low speeds
- less dense than solids

Question 4

what are the particles like in gases

Answer 4

• almost no forces of attraction
• have more energy than in the liquid or solid state
• they are free to move in random drections at high speeds
• they have low densities

Question 5

what is density a measure of

Answer 5

a measure of compactness

Question 6

what does the density of an object depend on

Answer 6

what its made out of
dense material has particles packed tightly together

Question 7

practical to find the density of a solid

Answer 7

• use a balance to measure the solids mass
• for some shapes you can find the volume by using a formula
• tricker shaped soild you can find the volume by submerging it in eureka can filled with water. the water displaced by the object will be transferred to a measuring cylinder
• volume of water in measuring cylinder is the objects volume
• calculate the denisty by using the euation d=m/v

Question 8

practical for finding the density of a liquid

Answer 8

• place a measuring cylinder on a balance a zero the balance
• pour 10ml of the liquid into a meauring cylinder and record the mass
  -pour another 10ml and record the total volume and mass
• repeat until cylinder is full
• for each measurement use the foruma to find the density
• take and average at the end

Question 9

what is the internal energy of a system

Answer 9

the total energy that its particles have in their kinetic and potential energy stores

Question 10

what does heating do to internal energy

Answer 10

heating a system transfers energy to its particles so they gain energy in their kinetic stores and move faster which increases their internal energy

Question 11

what can heating a system lead to

Answer 11

a change in temperature or a chang in state

Question 12

what does a change of a systems temperature depend on

Answer 12

the size of teh change depends on the mass, what its made of and the energy input

Question 13

what does a change of state depend on

Answer 13

the substance has to be heated enough so the particles will have enough energy in theit kinetic energy stores to break the bonds holding them together

Question 14

is a change of state a physical or chemical change

Answer 14

its a physical change as the substance is still the same just in a different form

Question 15

what happens when you reverse a change of state

Answer 15

the substance will return to its orginal form and gain back its orginal properties

Question 16

why is mass conserved in a change of state

Answer 16

the number of particles dont change they are just arranged differently- no mass is lost

Question 17

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

Answer 17

latent heat

Question 18

what do the flat spots on a heating graph represent

Answer 18

it shows where energy is being transfered by heating but its not being used to change the temperature

Question 19

when a substance is melting or boiling what is the energy used for

Answer 19

energy is still being put in so it increases the internal energy but the energys is used for breaking bonds between particles rather than raising the temperature - flat spots on heat graphs

Question 20

what happens when a substance is condensing or freezing

Answer 20

bonds are being formed between particles which releases energy

Question 21

what happens to the internal energy when substances are freezing or condensing

Answer 21

it decreases but the temperature doenst decrease until all of teh substance had turned into a soild or liquid. - flat spots show this

Question 22

what is the specific latent heat of a substance

Answer 22

the amount of energy needed to change 1kg of it from one state to another without chnaging its temperature

Question 23

what is the specific latent heat called for changing between a solid and a liquid ( freezing or melting)

Answer 23

the specific latent heat of fusion

Question 24

what is the specific latent heat called for changing between a liquid and a gas ( evaporation and condensation)

Answer 24

• specific latent heat of evaporation

Question 25

what are particles like in gases

Answer 25

free to move around

Question 26

what happens when gas particles move at high speeds

Answer 26

they bang into each other and what ever else is in the way - when they collide with something a force is exerted on it - this is pressure

Question 27

in a sealed container what is the outward gas pressure

Answer 27

the total force exerted by all the particles in the gas on a unit area of the container walls

Question 28

for a gas a constant volume what happens when you increase the temperature

Answer 28

you increase the pressure - particles travel quickerand hit sides of the container more - each particles has a larger momentum which means they exert a large force

Question 29

what happens if gases are heated in a expandable container

Answer 29

the volume increases

Question 30

what is the unit for density

Answer 30

kg/m3

Question 31

What happens to the temperature of a substance whilst it changes state?

Answer 31

The temperature remains constant

Question 32

How temperature and concentration affect a flexible container

Answer 32

An increase in force on the walls of the container would just cause the container to expand. Therefore, changing temperature or concentration will change the volume of the container, rather than the pressure of the gases inside.