By hand, measure 100 cm³ of water into a copper can, clamp it above a spirit burner, read the thermometer and weigh the burner with its cap on. Light the wick, stir until the water is about 20 °C warmer, put the flame out with the cap and weigh again. Repeat with a second alcohol, then work out the energy given out per gram of each fuel and explain why your values fall short of the data book. Every attempt uses a different pair of fuels. Allow about 30 minutes.
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The right unit for every row (°C or g), temperatures to the same precision and masses to 2 decimal places, readings for each fuel that match your thermometer and balance with 100 cm³ of water, rises and masses burned by subtraction, and a rise of about 20 °C with both fuels.
The energy transferred to the water (100 × 4.2 × rise, in J), the energy per gram in kJ/g from your own values, and both answers to 2 or 3 significant figures.
The fuel that gave out more energy per gram in your results, and why: the same rise from a smaller mass of fuel.
Why the cap goes back on (alcohols evaporate), why your value is lower than the data book (heat loss, incomplete combustion), an improvement with a reason, a variable to keep the same, and a safety precaution.
The marking follows the conventions in published Cambridge mark schemes. The experiments, readings and wording on this page are our own.