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Stearic acid, CH₃(CH₂)₁₄COOH, is a common saturated fatty acid - VCE - SSCE Chemistry - Question 1 - 2003 - Paper 1
Question 1
Stearic acid, CH₃(CH₂)₁₄COOH, is a common saturated fatty acid. a. What is meant by the term ‘saturated’? b. Stearic acid can be used as a source of energy. Write... show full transcript
Worked Solution & Example Answer:Stearic acid, CH₃(CH₂)₁₄COOH, is a common saturated fatty acid - VCE - SSCE Chemistry - Question 1 - 2003 - Paper 1
Step 1
What is meant by the term ‘saturated’?
Answer
The term 'saturated' refers to a type of fatty acid that contains no carbon-carbon double bonds. In saturated fatty acids, all carbon atoms are fully bonded to hydrogen atoms, which distinguishes them from unsaturated fatty acids that have one or more double bonds. This full saturation generally makes saturated fats solid at room temperature.
Step 2
Write a chemical equation for the complete reaction between oxygen and stearic acid.
Answer
The complete combustion of stearic acid can be expressed in the following chemical equation:
This equation shows that one molecule of stearic acid reacts with 26 molecules of oxygen to produce 18 molecules of carbon dioxide and 18 molecules of water.
Step 3
Step 4
How does the additive prevent oils becoming rancid?
Answer
Antioxidants prevent oils from becoming rancid by inhibiting the oxidative processes that lead to rancidity. They achieve this by reacting preferentially with oxygen, thereby reducing the availability of oxygen that can react with the fats in the oils. This slows down the rate of oxidation and prolongs the shelf life of the oils.