Which one of the following amino acids is likely to be most polar in an aqueous solution at pH 7?
- glutamic acid
- glycine
- leucine
- valine - VCE - SSCE Chemistry - Question 6 - 2012 - Paper 1
Question 6
Which one of the following amino acids is likely to be most polar in an aqueous solution at pH 7?
- glutamic acid
- glycine
- leucine
- valine
Worked Solution & Example Answer:Which one of the following amino acids is likely to be most polar in an aqueous solution at pH 7?
- glutamic acid
- glycine
- leucine
- valine - VCE - SSCE Chemistry - Question 6 - 2012 - Paper 1
Step 1
Identify the Amino Acids and Their Properties
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Answer
In order to determine which amino acid is the most polar at pH 7, we will analyze the properties of each amino acid listed: glutamic acid, glycine, leucine, and valine. At pH 7, amino acids will have specific ionization states that influence their polarity due to the presence of functional groups.
Step 2
Assess Glutamic Acid
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Answer
Glutamic acid contains a carboxylic acid group, which is deprotonated at pH 7, making it negatively charged. This contributes to its overall polarity.
Step 3
Assess Glycine
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Answer
Glycine is the simplest amino acid, with a hydrogen as its side chain. It is zwitterionic at pH 7 but is less polar compared to other options due to the lack of additional polar functional groups.
Step 4
Assess Leucine
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Answer
Leucine contains a branched aliphatic side chain, which is hydrophobic. This makes leucine less polar in aqueous solutions.
Step 5
Assess Valine
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Answer
Valine also has a branched aliphatic chain and is similarly hydrophobic, making it less polar than glutamic acid.
Step 6
Conclusion
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Answer
Among the amino acids listed, glutamic acid is the most polar at pH 7 due to its negatively charged carboxylate group, whereas glycine, leucine, and valine are comparatively less polar.
