3 - particle model of matter

Question 1

how do you find the density of a solid object - practical

Answer 1

• use a balance and measure its mass
• measure length,width,height with ruler and calculate volume
• if irregular solid you can find volume by submerging in eureka can filled with water and it will displace the water and transfer to a measuring cylinder
• use formula to find density

Question 2

how do you find the density of a liquid - practical

Answer 2

• put measuring cylinder on balance at 0
• pour 10 ml of liquid into it and record mass
• repeat this until cylinder is full and measure total mass and volume each time
• use the formula and take the average

Question 3

whats internal energy

Answer 3

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

Question 4

whats it called when you go from a solid to a gas

Answer 4

sublimating

Question 5

what happens when you change state

Answer 5

mass is conserved

Question 6

what is latent heat

Answer 6

the energy needed to change state of a substance

Question 7

changing state when melting or boiling - latent heat and flat spots

Answer 7

1. when melt or boil you put energy in so increase internal energy
2. this energy used for breaking intermolecular bonds - not raising the temp
3. flat spots on the graph - energy used to change state which means there is not enough to change temperature too

Question 8

changing state when condensing or freezing

Answer 8

1. when condensing or freezing bonds form which releases energy
2. internal energy decreases but temp doesnt go down
3. flat spots - show this energy tranfer

Question 9

whats the specific latent heat

Answer 9

amount of energy needed to change 1kg of a substance from one state to another without changing its temperature

Question 10

whats the specific latent heat of fusion and vaporisation

Answer 10

1. fusion - changing between a solid and liquid - melt or freeze
2. vaporisation - changing between a liquid and gas - evaporate or boil or condense

Question 11

effect of temperature on a gas

Answer 11

if you increase the temperature the average speed of its particles increases bc their kientic energy increases

Question 12

how do you increase the pressure of a gas

Answer 12

• faster particles
• more frequent collisions

Question 13

what happens when gas particles collide

Answer 13

they exert a force

Question 14

whats the outward pressure of a gas

Answer 14

in a sealed contained the outward pressure of gas = the total force exerted by all of the gas particles on an area of the container walls

Question 15

pressure and volume relationship

Answer 15

inversely proportional

Question 16

whats the effect of doing work on a gas and what is doing work

Answer 16

doing work - transferring energy by applying a force
- doing work on a gas increases its internal energy which increases its temp

Question 17

solids

Answer 17

• strong forces of ATTRACTION
• fixed regular arrangement of particles
• vibrate

Question 18

liquids

Answer 18

• weak forces of ATTRACTION
• close together but can move past each other in irregular arrangements
• random directions move

Question 19

gas

Answer 19

• almost no forces of ATTRACTION
• more energy than solids of liquids so free to move random directions at high speed

Question 20

energy with bonds forming and bond breaking

Answer 20

forming bonds - releases energy
breaking bonds - requires energy