1.8 Required practical: thermal insulation
9 exam questions worth 18 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
0 / 18
A student investigates how well different materials insulate a beaker of hot water. State the independent variable.
Mark scheme
type of insulating material (used to wrap the beaker) / thickness of insulator
Model answer
The type of insulating material.
State two control variables in this investigation.
Mark scheme
any two from: starting temperature (of the water); volume / mass of water; size / type of beaker; room temperature; thickness of insulator (if comparing materials); lid on / off
Model answer
The starting temperature of the water and the volume of water.
Explain why the student puts a lid on each beaker.
Mark scheme
energy is lost through the top / by evaporation / convection (1); so the test is fair / only the insulator affects the cooling (1)
Model answer
A lot of energy would be lost through the top of the beaker, so a lid is needed to make sure the different insulators are the only difference.
Describe the cooling curve of the best insulator, compared with the others.
Mark scheme
the temperature falls most slowly (1); the curve has the shallowest gradient / is the flattest (1)
Model answer
The curve is the flattest, because the temperature falls most slowly and the gradient is smallest.
Suggest one safety precaution the student should take, and explain why.
Mark scheme
any sensible precaution (1) with reason (1): e.g. carry hot water carefully / keep beakers away from the edge of the bench so that nobody is scalded
Model answer
Keep the beakers away from the edge of the bench so they are not knocked over and nobody is scalded.
The student's results for one insulator are very different when the experiment is repeated. Suggest two ways to improve the reliability of the results.
Mark scheme
repeat the experiment and calculate a mean (1); control variables more carefully e.g. same start temperature / use a temperature sensor and datalogger (1)
Model answer
Repeat the experiment several times and calculate a mean, and use a temperature sensor with a datalogger to record readings more accurately.
In one test the water cooled from 80 °C to 56 °C in 12 minutes without insulation. With insulation, it cooled from 80 °C to 68 °C in 12 minutes. Calculate the rate of cooling for each, and compare them.
Mark scheme
without insulation: 24 ÷ 12 = 2.0 °C per minute (1); with insulation: 12 ÷ 12 = 1.0 °C per minute (1); the rate of cooling is halved / the insulation reduces the rate of cooling by half (1)
Model answer
Without insulation: 24 / 12 = 2.0 °C per minute. With insulation: 12 / 12 = 1.0 °C per minute. The insulation halves the rate of cooling.
Explain why the cooling curve of the water is steepest at the start.
Mark scheme
the temperature difference between the water and the surroundings is greatest at the start (1); so the rate of energy transfer (cooling) is greatest then / it falls as the water cools (1)
Model answer
At the start the water is much hotter than the surroundings, so energy is transferred at the fastest rate and the temperature falls fastest.
Describe two changes to the investigation that would make the results more reliable.
Mark scheme
repeat the experiment and calculate a mean (1); use a temperature sensor and data logger / a thermometer with better resolution (1)
Model answer
Repeat the experiment three times and find a mean. Use a temperature sensor and data logger to record the temperature more accurately.
Found a mistake?