Particle model of matter

Question 1

what is the definition of density?

Answer 1

the mass per unit volume of a material
d= m/v

Question 2

describe the arrangment of a liquid?

Answer 2

Close together with lose bonds so they are able to flow over each other

Question 3

What always stays the same when an object changes state?

Answer 3

The mass of the object

Question 4

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

Answer 4

In a change of state it can be changed but chemical can not

Question 5

what is sublimation?

Answer 5

From solid to gas without changing into the liquid state

Question 6

when water boils in an open pan does the mass of the water appear to decrease?

Answer 6

some of the water with evaporate into water vapour so the mass of the pan will decrease but the mass of the whole system will remain constant

Question 7

explain the process of involved when a bathroom mirror fogs up

Answer 7

Hot water from the shower evaporates
the water vapour lands on the cool mirror and condenses back into liquid on the mirror surface

Question 8

what is the internal energy of a substance?

Answer 8

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

Question 9

How does heat affect the energy of a system?

Answer 9

Heat transfers energy to the system and increases the energy of the particles that make up the substance

Question 10

what 2 things can heating a substance do?

Answer 10

Raise it’s temp
change the state of matter

Question 11

What three factors determine the temperature change of a system?

Answer 11

The mass of the substance being heated
Type of material
Energy inputted into the system

Question 12

What is the equation to measure temperature change of an object?

Answer 12

Temperate change = mass x specific heat latency x heat energy

Question 13

define specific heat capacity?

Answer 13

The amount of energy needed to heat 1kg of a substance by 1oC

Question 14

How does the internal energy of an object change when a change of state occurs?

Answer 14

The internal energy will decrease (e.g liquid turning back into a solid will hold less energy)
But the overall temperature of the substance stays the same

Question 15

Define specific latent heat

Answer 15

The amount of energy needed to change the state of a substance (with no change in temperature ) Means to increase the internal energy of a substance so it changes the state

Question 16

equation for specific latent heat?

Answer 16

energy needed to change state = mass x specific latent heat

Question 17

what is the specific latent heat of fusion?

Answer 17

The energy required to change 1kg of a solid into a liquid without a change in temperature

Question 18

What is the specific latent heat of vaporisation?

Answer 18

The energy required to change 1kg of a liquid into a gas state without a change in temperature

Question 19

What is the motion of molecules of gas?

Answer 19

a constant random motion

Question 20

what factor affects the kinetic energy of gas molecules?

Answer 20

The temperature of the substance, higher temp = higher average kinetic energy of the gas molecules

Question 21

what effect does increasing the temperature have on the pressure of a gas?

Answer 21

Pressure of gas will increase as temperature increases

Question 22

Why does pressure increase as temperature increases?

Answer 22

Kinetic energy increases so therefore more collisions between gas molecules occur creating greater momentum, greater force and therefore more pressure

Question 23

If gas A is at a low pressure and gas B is at a high pressure what can be said about the amount of collisions in each gas?

Answer 23

The gas molecules in gas A have lower kinetic energy so therefore have less frequent collisions with other molecules
The gas molecules in Gas B have higher kinetic energy so therefore have a higher frequency of collisions with each other

Question 24

Describe the force that the pressure of a gas exerts on the walls of it’s container

Answer 24

the force of the molecules hits the container at a right angle, the force increases as the pressure increases

Question 25

Explain how increasing the volume of a gas decreases pressure

Answer 25

Molecules are more spread out so fewer collisions occur
the rate of momentum decreases and so the force exerted on the container decreases causing a lower pressure

Question 26

what is the unit used for pressure

Answer 26

Pascal (Pa)

Question 27

What increases when you work on a gas?

Answer 27

the internal energy of a gas which can also lead into an increase in temperature

Question 28

why does the temperature of air in an air pump increase when it is pumped?

Answer 28

force is put on the gas (work done) to compress it, this increases it’s internal energy so also increases the kinetic energy of the gas molecules
with kinetic energy increased so does the temperature increase