P3

Question 1

Describe the particle theory of a solid

Answer 1

– Strong forces of attraction hold the particles close together in a fixed, regular arrangement
– particles don’t have much energy so we can only vibrates around this fix positions
– the density is generally the highest in the state as the particles are close together

Question 2

Describe the particle theory of a liquid

Answer 2

– Weaker forces of attraction between the particles
– particles close together but can move past each other, and form irregular arrangements
– for any given substance, in the liquid state its particles will have more energy than in the solid-state
– move in random directions at low speeds
– generally less dense than solids

Question 3

Describe the particle theory of gases

Answer 3

– Almost no forces of attraction between the particles
– for any given substance, the gas state particles have more energy then in the solid-state or liquid state
– free to move and travel in random directions at high speeds
– low densities

Question 4

What is density

Answer 4

A measure of how compact a substances – relates the mass of a substance to how much space it takes up – mass per unit volume

Question 5

What is the equation and units for density

Answer 5

KG/m 3

Mass (KG)/volume (M3)

Question 6

What does the density of an object depends on

Answer 6

What it is made out of

Question 7

List the three states in order of density lowest to highest

Answer 7

Gas
Liquids
Solid

Question 8

What happens to density if you compress the material

Answer 8

– Particles move closer together

– more dense – not changing mass but decreasing volume

Question 9

How would you find the density of a solid object

Answer 9

– Use mass balance to measure mask
– find volume either using formula e.g. widthxlengthxheight
– or submerge it in eureka can filled of water – water displaced by object will be transferred to measuring cylinder
– record the volume of water in measuring cylinder
– divide Mass by the volume to find its density

Question 10

How would you find the density of a liquid

Answer 10

– Place measuring cylinder on mass balance and zero the balance
– for10 mL of the liquids into measuring cylinder and record liquids mass
– pour another 10 mL into the measuring cylinder and record the total volume and mass
– repeat until measuring cylinder is full
– for each measurement use the formula to find the density
– take an average of your calculated density is to get an accurate value for the density of the liquid

Question 11

What happens when you increase the temperature of a gas

Answer 11

– Particles in gas are constantly moving with random directions and speeds you like – if you increase the temperature, you transfer energy into the kinetic energy stores of its particles
– temperature of gas is related to average energy and kinetic energy stores of particles in the gas – the higher the temperature the higher the average energy
– as you increase the temperature, average speed of its particles increases as the energy and part of the kinetic energy store is half times mass times velocity squared

Question 12

What happens when gas particles collide

Answer 12

– They exert a force and so a pressure

Question 13

What is the outwards gas pressure in a sealed container

Answer 13

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

Question 14

How can you increase the pressure of the gas and how does this work

Answer 14

– First of particles and more frequent collisions both lead to an increase in net force and so gas pressure
– heat them up – if volume is kept constant then increasing temperature will increase the speed of the particles and so the pressure

Question 15

How could you increase the pressure of a gas if temperature is constant

Answer 15

Decrease the volume as the particles will get closer together and hit the walls of the container more often

Question 16

What is the relationship between pressure and volume in gases

Answer 16

Inversely proportional – at a constant temperature, when volume goes up pressure goes down

Question 17

For a gas of fixed mass at a constant pressure what is the relationship between pressure and volume and what are the units

Answer 17

pV = constant

P = pressure in pascals - Pa
V = volume in m3

Question 18

What happens when the pressure changes of a gas inside A container which can easily change its size

Answer 18

– The pressure of the gas causes a net outwards force at right angles to the service of its container
– also falls on the outside of the container due to pressure of gas around it
– any change in pressure will cause the container to compress or expand due to the overall force

Question 19

What happens if a helium balloon is released

Answer 19

– Atmospheric pressure decreases with height
– so pressure outside the balloon decreases
– causes balloon to expand until the pressure inside drops to the same as the atmospheric pressure

Question 20

What happens if you transfer energy by applying force on a gas and what does this do

Answer 20

– You do work

– doing work on the gas increases its internal energy – which can increase its temperature

Question 21

How can you do work on a gas and what is an example of its affect

Answer 21

– Mechanically e.g. with bike pump
– gas supplies pressure to the plunger of the pump and so exerts a force on it
– work has to be done against this force to push down the plunger
– transfers energy to the kinetic energy stores of the gas particles increasing the temperature
– if pump is connected to the tire, you should feel the tire getting warmer

Question 22

What does doing work on a gas do

Answer 22

Increases the internal energy of the gas and can cause an increase in the temperature