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6 (a) Explain one advantage of using biodiesel made from plant oils compared with using fossil diesel made from crude oil - AQA - GCSE Chemistry - Question 6 - 2017 - Paper 1
Question 6
6 (a) Explain one advantage of using biodiesel made from plant oils compared with using fossil diesel made from crude oil. 6 (b) Plant oils are used in emulsions to... show full transcript
Worked Solution & Example Answer:6 (a) Explain one advantage of using biodiesel made from plant oils compared with using fossil diesel made from crude oil - AQA - GCSE Chemistry - Question 6 - 2017 - Paper 1
Step 1
Explain one advantage of using biodiesel made from plant oils compared with using fossil diesel made from crude oil.
Answer
Biodiesel is carbon neutral because it releases carbon dioxide that was previously absorbed by plants during photosynthesis. This means that the net increase of CO₂ in the atmosphere is zero, making it environmentally friendly.
Step 2
Explain how an emulsion of water and oil is formed.
Answer
An emulsion forms when an emulsifier is shaken with a mixture of water and oil. The hydrophilic end of the emulsifier molecule dissolves in water, while the hydrophobic end dissolves in oil, creating stable droplets of one liquid dispersed in the other. This process helps to achieve a consistent texture in food products.
Step 3
Step 4
Describe and explain what happens to plant oils when they react with hydrogen in the presence of a nickel catalyst at about 60 °C.
Answer
When plant oils react with hydrogen, the hydrogen adds to the carbon-carbon double bonds in the oils. This process breaks the bonds and transforms unsaturated oils into saturated ones, which may be solid or have higher melting points at room temperature. This process is known as hydrogenation and results in oils that remain stable and are less prone to rancidity.