A student investigates the time taken for ice cubes to melt when they are placed in a beaker of hot water. Plan an experiment to investigate how the thickness of the cardboard insulation around a beaker affects the time taken for the ice cubes in the beaker to melt. You are not required to do this experiment. The following apparatus is available: 250 cm³ beaker supply of hot water supply of ice cubes thermometer stopwatch supply of 2 mm thick cardboard sheets. In your plan you should: • explain briefly how to carry out the investigation • state the key variables to keep constant • draw a table with column headings to show how to display the readings • explain how to use your readings to reach a conclusion.

Mark scheme

Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.

1. [1] MP1: insulate / wrap / cover the beaker with cardboard, add hot water, and place the ice cube(s) in the water ;
2. [1] MP2: measure the time taken for the ice to melt/ (start timing when the ice is put in the water and) stop the stopwatch when the ice has melted;
3. [1] MP3: repeat with at least 4 more layers of insulation ;
4. [1] MP4: Any one from: initial / starting temperature of the water, mass / volume / number / size of ice cubes (per test), starting temperature of ice cubes, volume/mass / amount of water in the beaker, room temperature ;
5. [1] MP5: table with columns for thickness of insulation / number of sheets / layers of insulation and time with appropriate units ;
6. [1] MP6: Any one from: compare the readings to see if the thickness (of the insulation) has any effect on the time taken for the ice to melt, plot a graph of thickness (of insulation) against time taken (for the ice to melt), (use the table of results to) compare the time taken to melt with the thickness (of the insulation);