TOPIC 3 - PARTICLE MODEL OF MATTER

Which type of error would have been caused if the student s eye was not in line with the level of the water when measuring it from a measuring cylinder?

random error

Describe a method the student could use to determine the density of the rock

• measure the mass using a balance/ scales
• part fill a measuring cylinder with water + measure inital volume
• place rock in water + measure final volume 
• volume = final volume - initial volume
• fill a displacement/ eureka can with water level with spout; place rock in water + collect displaced water
• measuring cyclinder used to determine volume of displace volume
• measure mass using a balance
• mass/ volume = density

Explain why the pressure increased when a plunger is pushed into a syringe

• particles are closer together
• frequency of collision between air particles + syringe walls increased
• large total force on a smaller surface area

How would the time taken for the wire to melt be affected if some energy was transferred to the surroundings?

time taken would increase; more energy would need to be transferred

Explain why the pressure increases as more air is pumped into the tyre

• more air particles in the tyre
• greater number of collisions with tyre walls per second
• so more force across same area

The air pressure in a car tyre changes if the temperature of the air in the tyre increases

• the air particles have greater kinetic energy
• so more collisions with tyre walls per second
• greater force in each collision
• greater force per square metre/ on a given area causes greater pressure

The specific heat capacity of ice is less than the specific heat capacity of water. Explain how the graph above shows this

the gradient for the ice is steeper than the gradient for the water; which means that less energy is needed to increase the temperature by a fixed amount

The specific latent heat of fusion of ice is less than the specific latent heat of vaporisation of water. Explain how the graph above shows this

the water took more time to vaporise than ice to melt; so less energy is needed to change the state from solide to liquid than from liquid to vapour

The student only measured the volume of each fruit once. The volume measurements cannot be used to show that the method to measure volume gives precise reading - why?

repeat readings are needed to show that the readings are similar/ close together

When the volume of gas in the syringe increased, the pressure on the inside walls of the syringe decreased

there are less frequent collisions of particles + the wall of the syringe; causing a lower average force on the walls of the syringe; and pressure is the total force per unit area

describe the movement of the gas particles in the balloon

random directions; with a range of speeds

Why is a mircometre better than a metre ruler?

a metre ruler has a lower resolution; so is less accurate

Explain how the zero error may be corrected after reading

record the value of the zero error where there is nothing to be measured; subtract the value of the zero error

Explain how the internal energy of the water changes as it is heated from 20 °C to 25 °C

• the kinetic energy of the particles increases
• which increases the internal energy of the water

How is the particle model used to explain the difference in density between a liquid and a gas?

Particles in a gas have more potential energy than particles in a liquid

A student measured the mass of boiling water that was turned into steam in five minutes. Explain how the student could use this information to estimate the power output of the Bunsen burner in watts

• Energy given to water E = mL 
• Power output = energy transferred/ time
• Power output = change in mass x specific latent heat/ time
• time should be converted to seconds/ use 300 seconds

Give two reasons why taking repeat readings could provide more accurate data

• calculate a mean; reduce effect of random errors; identify + remove anomalies

The internal energy of the air increases as the tyre is inflated - why?

work is done on the air in the tyre; so the temperature of the air increase