You were given three samples containing lipids and have been tasked to add Br2 solution until a color change is observed. Sample A required 5 mL of bromine before a visible color change. Sample B changed color almost immediately. Sample C required 12 mL while sample D needed 3 mL for a color change to be observed. Rank the samples in order of increasing degree of unsaturation and explain why?
The way this question is worded is a bit confusing. When you say color change you don't make it clear whether it is the Br2 water that is changing color or the lipid that is changing color. Here is the way I understand the statement. You will add Br2 water (which is brown-red) to the solution. If the solution is saturated the Br2 water color remains and changes the solution immediately. If a degree of un- saturation is there the Br2 color goes away. Another thing is you said 3 samples but you listed 4.
So, sample A has unsaturation. Either double or triple bonds. Sample B has none. Sample C has the most unsaturation and sample D is between A and B. Unsaturation can be in the form of double bonds or triple bonds.
To rank the samples in order of increasing degree of unsaturation, we need to understand the concept of unsaturation in lipids and how it relates to the reaction with Br2 solution.
Unsaturation in lipids refers to the presence of carbon-carbon double bonds. When lipids containing double bonds react with bromine (Br2) solution, the orange-brown color of bromine gets decolorized. This decolorization occurs because the double bonds in the lipids break open and the bromine atoms add to the carbons, forming a colorless product.
Based on the information provided, we can analyze the results for each sample:
1. Sample B changed color almost immediately: This suggests that Sample B contains a high degree of unsaturation, as it rapidly reacted with the Br2 solution. The quick color change indicates the presence of a significant amount of double bonds.
2. Sample D needed 3 mL for a color change: This indicates that Sample D contains a lesser degree of unsaturation compared to Sample B. It required less bromine for a visible color change, suggesting a lower number of double bonds.
3. Sample A required 5 mL of bromine before a visible color change: This suggests that Sample A has a lower degree of unsaturation compared to both Samples B and D. It required more bromine for the color change, indicating a higher number of double bonds compared to Sample D but fewer than Sample B.
4. Sample C required 12 mL for a color change to be observed: This indicates that Sample C has the lowest degree of unsaturation among all the samples. It required the most bromine for a visible color change, suggesting the presence of the fewest double bonds.
Therefore, the ranking of the samples in increasing order of degree of unsaturation would be: Sample C < Sample A < Sample D < Sample B.
In summary, the ranking is based on the amount of bromine (Br2) solution needed for a visible color change. Samples B, D, A, and C have decreasing degrees of unsaturation, respectively, with Sample B having the highest unsaturation.