Edexcel IGCSE Physics 复习笔记 5.2.3 Core Practical: Investigating Changes of State

Aim of the Experiment

• The aim of this experiment is to investigate how the temperature of ice varies when it changes state from a solid to a liquid

Equipment List

• Resolution of measuring equipment:
  • Thermometer = 0.1 °C
  • Stopwatch = 0.1 s

   

Method

Apparatus used to heat ice and measure its temperature as it melts

1. Place the ice cubes in the beaker (it should be about half full)
2. Place the thermometer in the beaker
3. Place the beaker on the tripod and gauze and slowly start to heat it using the bunsen burner
4. As the beaker is heated, take regular temperature measurements (e.g. at one minute intervals)
5. Continue this whilst the substance changes state (from solid to liquid)

• An example results table is shown below:

Analysis of Results

• Plot a graph of the temperature (y-axis) against time (x-axis)
• The graph will show regions where:
  • The temperature of the ice cubes increases
  • There is no temperature change (even though the ice cubes continue to be heated)
  • This should occur at 0 °C, where the ice is melting from solid to liquid

   

A graph of temperature against time will show a flat region where the ice is melting

Evaluating the Experiment

Systematic Errors:

• Measurements of temperature from the thermometer keeping it at eye level, to avoid parallax errors
  • Ensure the thermometer is held vertically in the beaker

   

Random Errors:

• Ensure there are enough ice cubes to surround the thermometer in the beaker, and only begin the experiment when the temperature is below 0 °C
  • This is to ensure readings of temperature are as accurate as possible

   

Safety Considerations

• Wear goggles while heating water
• Place the bunsen burner, with the beaker and tripod, on a heatproof mat to avoid surface damage
• Make sure to stand up during the whole experiment, to react quickly to any spills