section 7 - matter

Question 1

solids

Answer 1

strong forces of attraction hold particles close together in a fixed, regular arrangement
the particles don’t have much energy in their kinetic stores, so they can only vibrate about their fixed positions

Question 2

liquids

Answer 2

the forces of attraction between particles are weaker than in solids
the particles are close together but can move past each other and form irregular arrangements
they have more energy in their kinetic stores than particles in solids
they move in random directions at low speeds

Question 3

gases

Answer 3

there are almost no forces of attraction between particles
they have more energy in their kinetic stores than liquids
they are free to move and travel in random directions at high speeds

Question 4

specific heat capacity

Answer 4

the change in energy in the thermal store of the substance needed to raise 1kg of that substance by 1˚C

water’s is 4200J/kg˚C (quite high)

Question 5

SHC of water practical

Answer 5

• find the mass of the insulating container with a mass balance
• fill the container with water and measure the mass again, find the difference to get the mass of water
• add an electric immersion heater connected to a joule meter which is connected to a power supply and a thermometer
• make sure the joule meter reads 0 and add a lid to the container, measure the water temp and turn on the power
• after a 10˚C increase stop the experiment and record the energy on the joulemeter
• calculate water’s SHC with the equation
• repeat at least thrice and calculate a mean

Question 6

specific latent heat

Answer 6

the amount of energy needed to change 1kg of a substance from one state to another, without changing it’s temperature

Question 7

SLH of water practical

Answer 7

• fill a beaker with crushed ice
• place a thermometer in the beaker and record the temperature
• gradually healthy the beaker with a bunsen turner
• record the temperature and state every 20 seconds
• continue until the water begins boiling
• plot a graph of temperature against time

Question 8

specific latent heat of fusion

Answer 8

changing between a solid and liquid, so melting/freezing

Question 9

specific latent heat of vaporisation

Answer 9

changing between a liquid and a gas, so evaporating/boiling/condensing

Question 10

absolute zero

Answer 10

-273˚C, the start of the Kelvin temperature scale

at absolute zero, particles have as little energy in their kinetic stores as it is possible to get and It is the coldest that anything can ever get

˚C to K = add 273
K to ˚C = subtract 273

Question 11

why does gas exert a force on it’s container

Answer 11

there are collisions between the particles and the container walls
they happen on random directions, but add together to form the net force at right angles to the walls of the container

Question 12

doing work on a gas

Answer 12

work can be done on a gas mechanically - e.g. with a bike pump

the gas exerts pressure on the plunger of the pump and so exerts a force on it, work has to be done against this to push down on the plunger

this transfers energy to the kinetic energy stores of the gas particles, increasing the internal energy and therefore temperature