Required practical

Temperature-time graph for melting ice

There are different ways to create a temperature-time graph for melting ice. In this required practical activity it is important to:

  • measure and observe the change in temperature accurately
  • use the appropriate apparatus and methods to measure the changes in temperature over time of crushed ice

Aim of the experiment

To obtain a graph showing changes in temperature over time for heated ice.

Method

A heater rests in an insulated calorimeter and touches crushed ice whilst a thermometer measures the temperature.

  • Place 50 grams of crushed ice straight from the freezer into the calorimeter.
  • Place the immersion heater into the central hole at the top of the calorimeter.
  • Clamp the thermometer with its bulb in the ice but near the top of the ice.
  • Record the temperature of the ice.
  • Connect the heater to the power supply and joulemeter, turn it on and record the temperature every 20 seconds.
  • Continue until the thermometer bulb is no longer under the level of the water.

Results

Record results in a suitable table. The example below shows some suitable results.

Time (s)Initial temperature (°C)
0-5
20-1
400
......

Plot a graph of temperature against time. It will look something like this:

Graph measuring time against temperature, looking at the temperature changes between solid, liquid and gas for ice, water and steam.

Evaluation

  • The regions in which the line on the graph is horizontal represent a state change occurring.
  • Depending upon the power of the heater, the amount of insulation around the calorimeter, and the exact mass of ice at the start, the time needed for each stage may be different, but the shape of the graph should always be the same.

Hazards and control measures

HazardConsequenceControl measures
Hot immersion heater and waterBurn skinDo not touch when switched on. Position away from the edge of the desk. Allow time to cool before packing away equipment. Run any burn under cold water for at least 10 minutes.
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