This question is about the combustion of alcohols - AQA - GCSE Chemistry - Question 2 - 2017 - Paper 3

The diagram that shows an arrow for the overall energy change is diagram C. This indicates that energy is released during the combustion process.

To compare the energy released when methanol and ethanol are burned, the student should follow these steps:

1. Measure the Initial Mass of Alcohol:

   • Weigh the alcohol burner with methanol and record its mass.
   • Repeat with ethanol.

2. Measure the Initial Temperature of Water:

   • Fill the glass beaker with a known volume of water and measure the initial temperature using the thermometer.

3. Ignite the Alcohol:

   • Ignite the burner containing methanol to heat the water and ensure it's placed below the beaker.

4. Stir the Water:

   • Stir the water gently to ensure an even temperature distribution.

5. Measure Final Temperature:

   • After a suitable time (e.g., 5 minutes), record the final temperature of the water.

6. Repeat with Ethanol:

   • Replace methanol with ethanol in the burner and repeat the process, ensuring the same conditions are followed.

7. Record Data:

   • Finally, document the temperatures and masses to analyze the energy released by each alcohol.

To enhance the accuracy of the results obtained from the apparatus in Figure 3, the following improvements could be made:

1. Use a Lid or Insulated Container:

   • Place a lid on the glass beaker to reduce heat loss to the environment, ensuring more heat is retained in the water.

2. Minimize Heat Loss:

   • Use a metal container to absorb heat more effectively compared to a glass beaker.

3. Use a Digital Thermometer:

   • A digital thermometer could provide more precise temperature readings compared to a traditional one.

4. Control External Conditions:

   • Conduct the experiment in a controlled environment to minimize the effects of wind and temperature fluctuations.