Unit 8I (Heating and Cooling)

Question No. / Level / Mark
1(01) / 4 / 7
2(99) / 5 / 5
3(97) / 6 / 8
4(01) / 6 / 6
5(01) / 7 / 6
6(05) / 7 / 5

1.The diagram shows the parts of an iron.

(a)Choose words from the list below to fill the gaps in the sentences.

low high heat poor

sound gravity friction electricity

The bottom of the iron is made of steel because steel is a good

conductor of ……………………………, and because steel has a

…………………………… melting point.

The steel is polished until it is very smooth to reduce the force of

…………………………… between the iron andthe cloth.

3 marks

(b)Suggest what material the handle could be made from.

………………………………….

1 mark

Give a reason for your answer.

……………………………………………………………………………………….

1 mark

(c)The iron has three temperature settings.
The settings for different fabrics are shownbelow.

What might happen if nylon clothes are ironed on the setting?

……………………………………………………………………………………….

1 mark

(d)After it is switched on, the iron heats up. The time it takes to heat up is shown below.

Suggest the time to heat up on the setting.
Write your answer in the table.

1 mark

Maximum 7 marks

2.Some crushed ice at -20 C was placed in a beaker. A thermometer was put into the ice, and the beaker was heated gently for 15 minutes.

The graph shows how the reading on the thermometer changed over the 15 minutes.

(a)By how much did the temperature in the beaker change during the 15 minutes?

...... °C

1 mark

(b)Which letter on the graph shows:

(i)when the ice is melting? ......

1 mark

(ii)when the water is boiling?......

1 mark

(c)During the experiment, the beaker and its contents were quickly removed from the heat and weighed on a balance at the following times.

at 0 minutes

at 5 minutes

at 10 minutes

at 15 minutes

(i)At which two times would you expect the readings on the balance to be thesame?

...... minutes and ...... minutes

1 mark

(ii)Between which two of these times was the mass of the contents of the beaker changing most rapidly?

...... minutes and ...... minutes

1 mark

Maximum 5 marks

3.This question is about four chemical elements.

(a)The melting points and boiling points of the four elements are shown in the table. Complete the table to give the physical state, solid, liquid or gas, of each element at room temperature, 21°C.

element / melting point
in °C / boiling point
in °C / physical state at room
temperature, 21°C
bromine / –7 / 59
chlorine / –101 / –34
fluorine / –220 / –188
iodine / 114 / 184

4 marks

(b)Bromine can be a solid, a liquid or a gas depending on the temperature.
In which physical state will 10 g of bromine store the most thermal energy?

......

1 mark

(c)Is bromine a solid, a liquid or a gas when the arrangement of particles is:

(i)far apart and random? ......

1 mark

(ii)close together but random? ......

1 mark

(iii)close together in a regular pattern? ......

1 mark

Maximum 8 marks

4.(a)The table gives some of the properties of three substances: water, paraffin wax andnaphthalene.

substance / melting point
in °C / density
(mass of 1 cm3 in g)
water / 0 / 1.0
paraffin wax / 60 / 0.8
naphthalene / 80 / 1.2

Use the information in the table to help you answer parts (i) and (ii) below.

(i)Arif placed a ball of naphthalene in a beaker containing water kept at 70°C.
On diagram 1, draw the shape and position of the naphthalene ten minutes later.

2 marks

(ii)Arif repeated the experiment with a similar sized ball of paraffin wax.
On diagram 2, draw the shape and position of the paraffin wax ten minutes later.

2 marks

(b)Arif then melted some crystals of stearic acid in a beaker. He placed a temperature probe in the stearic acid and left the stearic acid to cool.
As the stearic acid cooled down its state changed.
What was the change in the state of the stearic acid as it cooled?

From ……………………………… to ………………………………

1 mark

(c)Arif plotted the following graph.

Which letter on the graph shows when the stearic acid started to change state?

…………

1 mark

Maximum 6 marks

5.(a)In an iron rod the particles vibrate. If one end of an iron rod is heated, the vibrating particles transfer energy to neighbouring particles which are not vibrating so violently.
What is this process called?

……….………………………………

1 mark

(b)An electric immersion heater is put at the bottom of a large tank of water.

The water next to the heater becomes warm.

(i)What will happen to the warmed water next to the heater?
Give a reason for your answer.

…………………………………………………………………………………

2 marks

(ii)Why can heat not be transferred in this way in an iron rod?

…………………………………………………………………………………

1 mark

(c)In a liquid, some of the particles have enough kinetic energy to escape from the surface.
This process happens even when the liquid is well below its boiling point.

(i)What is this process called? ……………………………………………….

1 mark

(ii)How will this affect the temperature of the liquid left in the container?

…………………………………………………………………………………

1 mark

Maximum 6 marks

6.John used an electrical heater to heat a cup of water. He kept stirring the water. When the temperature reached 20°C, he started his stopwatch and measured the temperature of the water every half minute.

He switched off the heater after 4 minutes, but continued to record the temperature.
His results are shown in the table.

One measurement is missing and another appears to be wrong.

Time (minutes) / Temperature (ºC)
0.0 / 20
0.5 / 26
1.0 / 31
1.5 / 36
2.0 / 41
2.5 / 46
3.0
3.5 / 57
4.0 / 56
4.5 / 58
5.0 / 59
5.5 / 59

(a)Use the results in the table to draw a graph on the grid.
Label the axes.
Plot the points and draw a smooth curve of best fit.

4 marks

(b)From your curve, estimate the temperature of the water after three minutes.

...... °C

1 mark

maximum 5 marks

Rainford High Technology College1