Particle motion & pressure in gases

Which of these changes of state describes sublimation?

Figure 12 shows a sealed aerosol can.

The sealed can is taken from a cold room into a warm room.

If the volume of the can remains the same, which of these does not change?

Figure 13 shows a storage heater.

The storage heater contains bricks.

The bricks are heated electrically.

The electrical heater supplies 210 kJ of energy to each brick in the storage heater.

One brick has a mass of 5.8 kg.

The specific heat capacity for the brick is 860 J/kg K.

Use this data to calculate the increase in temperature of the brick.

temperature increase =_........ °C

The actual temperature increase will be smaller than you calculated in (i).

Explain why the actual temperature increase will be smaller than the value in (i).

* (d) Describe an investigation to determine the value for the specific heat capacity of water.

Your answer should include details of

• the apparatus needed

• the experimental procedure

• how the value may be calculated from the measurements taken.

You may draw a diagram to help your answer.

Which of these means changing state from solid directly to gas?

An object has a mass of 7.22×10^–2kg and a volume of 2.69×10^–5m³.

Calculate the density, ρ, of the object.

Use the equation

State the unit.

density =_........ unit_........

Aluminium has a melting point of 660C.

The absolute zero of temperature is –273C.

Calculate the melting point of aluminium in kelvin.

melting point of aluminium =_........ K

Describe the motion of particles in liquid aluminium (above 660C).

*(d) The table shows some properties of two materials used as thermal insulation.

The higher the R‑value, the better the thermal insulating properties of the material.

Assess which of these materials may be the more suitable to use as thermal insulation in a building.

Your answer should compare the properties of fibreglass and polystyrene given in the table.

Equations

Which of these means changing state from solid directly to gas?

An object has a mass of 7.22×10^–2kg and a volume of 2.69×10^–5m³.

Calculate the density, ρ, of the object.

Use the equation

State the unit.

density =_........ unit_........

Aluminium has a melting point of 660C.

The absolute zero of temperature is –273C.

Calculate the melting point of aluminium in kelvin.

melting point of aluminium =_........ K

Describe the motion of particles in liquid aluminium (above 660C).

A student determines the volume of a piece of metal by measuring the volume of water that it displaces.

The student wrote the following in his notebook.

The student’s description is incomplete.

Suggest two sentences that the student could have included to provide a more complete description of the correct procedure.

Explain the difference between the term ‘specific heat capacity’ and the term ‘specific latent heat’ when applied to heating substances.

Figure 10 shows some apparatus that may be used to determine the specific heat capacity of water.

A student measures the initial temperature of the water.

The power supply is switched on for 10 minutes and then switched off.

Explain how the student should then obtain an accurate reading for the final temperature of the water, to be used in the calculation of the specific heat capacity.

*(c) A container of gas is at room temperature.

The gas is then heated.

The volume of the container remains the same.

By considering changes in velocities of the gas particles, explain how the temperature increase affects

• the average kinetic energy of the particles

• the pressure the particles exert on the walls of the container.

Equations

Describe, in terms of particles, two differences between a solid and a liquid of the same substance.

Figure 3 shows the dimensions of a solid block of concrete.

Density of concrete, ρ, = 2100 kg / m³.

Calculate the mass of the concrete block.

Use the equation

m = ρ × V

mass of concrete block =_........ kg

Figure 4 shows a shed made mostly of concrete blocks.

State two practical ways to reduce heat loss from this shed.

On a very cold day, the temperature of the air is −4 °C.

Calculate the value of this temperature on the kelvin scale.

temperature =_........ K