Brainlag PlusThe Edexcel core practical: heating water with a spirit burner of ethanol, propanol, butanol and pentanol, working out the energy released per gram, and explaining the trend and why the results come out low.
What you do
A spirit burner of the alcohol heats water in a copper can clamped just above the wick.
- Measure a fixed volume of water (say 100 cm³, which is 100 g) into the can and record its temperature.
- Weigh the spirit burner with its cap on.
- Light it and heat the water, either for a fixed time or until the temperature has risen by a fixed amount (say 20 °C). Then put the cap on to put it out.
- Reweigh the burner straight away: the difference is the mass of alcohol burned.
- Repeat with each alcohol, using fresh water and the same can and height.
- Independent variable: the alcohol (how many carbon atoms it has).
- Dependent variable: the temperature rise (fixed time) or the mass burned (fixed rise).
- Control variables: the mass of water, the height of the can above the wick, the can, the starting temperature.
Safety: the alcohols are flammable. Keep the bottles closed and away from the flame, stand the burner on a heatproof mat and wear eye protection. The can gets hot.
The rest of this lesson and its 9 practice questions are in Plus.
Screen 1 of 4, free to read.
- 9 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards