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This question is about vegetable oils - AQA - GCSE Chemistry - Question 5 - 2016 - Paper 1
Question 5
This question is about vegetable oils. 5 (a) Explain why using vegetable oils as biofuels does not increase global warming. 5 (b) Describe how and explain why vege... show full transcript
Worked Solution & Example Answer:This question is about vegetable oils - AQA - GCSE Chemistry - Question 5 - 2016 - Paper 1
Step 1
Explain why using vegetable oils as biofuels does not increase global warming.
Answer
Using vegetable oils as biofuels is considered carbon neutral because:
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Carbon Dioxide Emission: When vegetable oils combust, they release carbon dioxide (CO₂) into the atmosphere. However, this CO₂ is part of a cycle. The plants from which the vegetable oil is extracted absorb CO₂ during their growth.
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No Net Increase: Consequently, there is no net increase in the percentage of carbon dioxide in the atmosphere. The CO₂ released when biofuels are burned was originally absorbed by the plants, balancing the cycle.
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Overall Impact: This process ensures that using vegetable oils does not contribute significantly to global warming when considering the lifecycle of carbon dioxide absorption and emission.
Step 2
Describe how and explain why vegetable oils are hardened for use in foods.
Answer
Vegetable oils are hardened through a process called hydrogenation, which involves:
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React with Hydrogen: Vegetable oils are reacted with hydrogen (hydrogenation) in the presence of a nickel catalyst at a temperature around 60°C.
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Unsaturation to Saturation: This process helps to convert unsaturated oils, which contain carbon-carbon double bonds, into saturated forms, allowing them to be solid at room temperature.
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Functional Purposes: The hardened oils have higher melting points and are used in various food applications such as margarine, which enhances texture, stability, and spreadability. It is important to note that hardened vegetable oils are not suitable for making butter.