Topic 7- Matter

Question 1

Density definition

Answer 1

A mass per unit volume as a measure of ‘compactness’ of a substance.

Question 2

Symbol for density

Answer 2

Rho (slanted p)

Question 3

Density equation

Answer 3

Mass/volume

Question 4

Density units

Answer 4

G/cm cubed

Kg / m cubed

Question 5

How does a solid float?

Answer 5

If it has a lower average density than the fluid.

Question 6

How do you find the density of a substance?

Answer 6

For a liquid: Use mass balance to measure mass of empty measuring cylinder.
Pour in liquid and measure mass again (mass difference=liquid mass).
Measure liquid volume on cylinder (1ml = 1 cm cubed).
For solid, work out volume by dimensions.

Question 7

How do you measure the density of an object without a regular shape?

Answer 7

Measure mass w mass balance.
Fill bottle w liquid of known density.
Place stopper on and dry outside, measure mass of bottle.
Empty bottle and place object into density bottle w same liquid.
Calculate volume of displaced water by taking the mass of the bottle with the object in and taking away the object’s mass, showing volume of water filling it. Take this away from the original mass of the bottle with just water in to find the displaced water mass, (1ml=1cm cubed). This shows the vol.

Question 8

Physical changes

Answer 8

Only the form of substance changes

Question 9

Chemical changes

Answer 9

New substances are created by reaction.

Question 10

Solid

Answer 10

Strong forces of attraction hold particles in close, fixed, regular arrangement. Particles have little energy in kinetic energy stores so vibrate about fixed positions.

Question 11

Liquid

Answer 11

Weaker forces of attraction between particles which are close together but can move past each other and form irregular arrangements. Have more energy than solid so move in random directions at low speeds.

Question 12

Gas

Answer 12

Almost no forces of attraction, most energy in kinetic stores, travel in random directions at high speeds.

Question 13

Where is the energy in a substance’s thermal energy store held?

Answer 13

By its particles in their kinetic energy stores.

Question 14

Temperature in kinetic theory

Answer 14

Way of measuring average internal energy of a substance.

Question 15

Specific heat capacity

Answer 15

The change in energy in the substance’s thermal store needed to raise the temperature of 1kg of that substance by 1°C.

Question 16

Equation relating mass, energy, specific heat capacity and temperature

Answer 16

Change in thermal energy= mass * specific heat capacity* temp change

Question 17

What’s specific heat capacity measured in?

Answer 17

J/kg°C

Question 18

How do you find the specific heat capacity of water?

Answer 18

Measure mass of insulating container w mass balance.
Fill w water and measure mass again (difference=water mass)
Connect joulemeter (at 0) to immersion heater in water w thermometer w lid on container.
Measure temp of water and turn on power.
When temp as increased by set temp, record energy on joulemeter

Question 19

Practical to show energy used in breaking intermolecular forces and energy produced in forming intermolecular bonds

Answer 19

Fill beaker w ice and thermometer (measure temp of ice)
W Bunsen, heat gradually and record temp every 20 secs and state of ice
Continue until begins to boil
Plot graph

Question 20

Specific latent heat

Answer 20

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

Question 21

Specific latent heat for cooling

Answer 21

Energy released by a change in state

Question 22

Specific latent heat for changing between a solid and a liquid

Answer 22

Specific latent heat of fusion

Question 23

Specific latent heat between liquid and a gas

Answer 23

Specific latent heat of vaporisation

Question 24

Equation linking thermal energy, mass and specific latent heat

Answer 24

Thermal energy = mass * specific latent heat

Question 25

What’s specific latent heat measured in

Answer 25

J/kg

Question 26

Relationship between pressure and volume

Answer 26

Inversely proportional

P1V1 = P2V2

Question 27

Absolute zero

Answer 27

-273°C

Start of Kelvin scale

Question 28

Conversion from °C to kelvin

Answer 28

+273

Question 29

Gas pressure

Answer 29

The total force exerted by the particles per unit area