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When molecular iodine, I₂, reacts with an unsaturated compound, one molecule of iodine adds across each double bond - VCE - SSCE Chemistry - Question 19 - 2008 - Paper 1
Question 19
When molecular iodine, I₂, reacts with an unsaturated compound, one molecule of iodine adds across each double bond. Unsaturated fatty acids react in this way with i... show full transcript
Worked Solution & Example Answer:When molecular iodine, I₂, reacts with an unsaturated compound, one molecule of iodine adds across each double bond - VCE - SSCE Chemistry - Question 19 - 2008 - Paper 1
Step 1
0.150 mol of a particular fatty acid reacts with exactly 0.300 mol of I₂.
Answer
To determine which fatty acid corresponds to the reaction with 0.300 mol of I₂, we recognize that each double bond in the fatty acid will react with one molecule of iodine. Thus, the mols of iodine (0.300 mol) will indicate the number of double bonds present.
Since 0.150 mol of fatty acid reacts with 0.300 mol of iodine, we can deduce that there are 2 double bonds in this fatty acid (as 0.300 mol I₂ / 0.150 mol fatty acid = 2).
Among the options given:
- Lauric acid: Contains no double bonds (Saturated).
- Linoleic acid: Contains 2 double bonds (unsaturated).
- Palmitoleic acid: Contains 1 double bond (monounsaturated).
- Arachidonic acid: Contains 4 double bonds (polyunsaturated).
Based on the analysis, the correct answer is B. linoleic.