Photo AI
This question is about the combustion of alcohols - AQA - GCSE Chemistry - Question 2 - 2017 - Paper 3
Question 2
This question is about the combustion of alcohols. 2 (a) What is the structure of methanol? Tick (✓) one box. CH₃OH CH₃CH₂OH CH₃CH₂CH₂OH CH₃CH₂CH₂CH₂OH 2 (b) Figu... show full transcript
Worked Solution & Example Answer:This question is about the combustion of alcohols - AQA - GCSE Chemistry - Question 2 - 2017 - Paper 3
Step 1
Step 2
Step 3
Describe how a student could use the apparatus in Figure 3 to compare the energy released when methanol and ethanol are burned.
Answer
To compare the energy released when burning methanol and ethanol using the apparatus in Figure 3, the student should follow these steps:
- Measure the initial mass of the alcohol (either methanol or ethanol) before burning.
- Measure the initial volume or mass of water in the glass beaker. This will be used to determine the amount of energy absorbed by the water.
- Record the initial temperature of the water using the thermometer.
- Ignite the alcohol burner containing methanol or ethanol beneath the glass beaker to heat the water.
- Stir the water gently during the heating process to ensure even temperature distribution.
- After a predetermined time or when a considerable temperature rise is noticed, the student should extinguish the flame and immediately measure:
- The final temperature of the water.
- The final mass of the alcohol burner to determine how much alcohol was used.
- Repeat the process with the other alcohol. By comparing the temperature changes and the amounts of alcohol burned, the student can deduce the energy released by each fuel.
Step 4
Explain how the apparatus in Figure 3 could be improved to obtain more accurate results.
Answer
To improve the accuracy of results obtained from the apparatus in Figure 3, the following modifications could be made:
- Use a lid or cover for the glass beaker to minimize heat loss to the surroundings, ensuring more energy is transferred to the water.
- Opt for a metal container instead of glass as it can improve heat conduction, allowing more efficient energy transfer to the water.
- Ensure that the thermometer used does not have a delay in readings, which can lead to unaccounted heat loss.
- Position the burner closer to the glass beaker to reduce heat loss during the combustion process. All of these improvements would lead to a more accurate measurement of the energy released during each alcohol's combustion.