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Propane, C3H8, is an alkane - OCR Gateway - GCSE Chemistry - Question 18 - 2023 - Paper 2
Question 18
Propane, C3H8, is an alkane. Propane undergoes complete combustion in oxygen. Carbon dioxide and water are made. (a) Write the balanced symbol equation for the com... show full transcript
Worked Solution & Example Answer:Propane, C3H8, is an alkane - OCR Gateway - GCSE Chemistry - Question 18 - 2023 - Paper 2
Step 1
Write the balanced symbol equation for the complete combustion of propane.
Answer
The complete combustion of propane can be expressed by the balanced chemical equation:
In this reaction, one molecule of propane reacts with five molecules of oxygen to produce three molecules of carbon dioxide and four molecules of water.
Step 2
The table shows the energy given out when 1 g of different alkanes burn.
Answer
From the table, we can observe the energies released by various alkanes when 1 gram is burned:
- Methane (1 carbon atom): 55.6 kJ
- Ethane (2 carbon atoms): 52.6 kJ
- Propane (3 carbon atoms): 50.4 kJ
- Butane (4 carbon atoms): 48.7 kJ
- Pentane (5 carbon atoms): 48.4 kJ
- Hexane (6 carbon atoms): 48.4 kJ
This data indicates that as the number of carbon atoms in the alkane increases, the energy released tends to decrease.