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The structure of one molecule of a compound is shown in Figure 10 - Edexcel - GCSE Chemistry - Question 7 - 2022 - Paper 1
Question 7
The structure of one molecule of a compound is shown in Figure 10. (a) What is the molecular formula of the compound in Figure 10? A B C D (b) The compound in ... show full transcript
Worked Solution & Example Answer:The structure of one molecule of a compound is shown in Figure 10 - Edexcel - GCSE Chemistry - Question 7 - 2022 - Paper 1
Step 1
Step 2
State why the compound is described as an unsaturated hydrocarbon.
Answer
The compound is described as an unsaturated hydrocarbon because it contains at least one double bond between carbon atoms. This double bond prevents it from being saturated with hydrogen, which is characteristic of alkenes.
Step 3
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Step 5
Discuss the complete and incomplete combustion of these alkanes and the trend in the energy changes they produced.
Answer
Complete combustion occurs when there is enough oxygen to convert all carbon in the fuel to carbon dioxide (CO₂) and all hydrogen to water (H₂O). The general reaction can be represented as:
ightarrow ext{CO}_2 + ext{H}_2O$$ Incomplete combustion occurs when there is insufficient oxygen, resulting in products such as carbon monoxide (CO) and soot (carbon black). The general incomplete combustion is: $$ ext{Alkane} + ext{O}_2 ightarrow ext{CO} + ext{H}_2O$$ From Figure 12, as the size of the alkane increases from methane to butane, the temperature change also increases. This trend indicates that larger alkanes release more energy upon combustion due to a higher number of carbon and hydrogen atoms, contributing more to the exothermic reaction. Methane and ethane have lower temperature changes compared to propane and butane, supporting the notion that increased molecular size correlates with higher energy outputs during combustion.