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The amino acid, alanine, dissolves in water - VCE - SSCE Chemistry - Question 9 - 2002 - Paper 1
Question 9
The amino acid, alanine, dissolves in water. In an aqueous solution with a pH = 7, alanine is acting as A. an acid only. B. a base only. C. neither an acid nor a ba... show full transcript
Worked Solution & Example Answer:The amino acid, alanine, dissolves in water - VCE - SSCE Chemistry - Question 9 - 2002 - Paper 1
Step 1
In an aqueous solution with a pH = 7, alanine is acting as
Answer
At a neutral pH of 7, alanine exists predominantly in its zwitterionic form, where it has both a positive and a negative charge. This allows it to act as both an acid and a base. In this state, the amino group ( ext{-NH}_2) can accept a proton (acting as a base), while the carboxyl group ( ext{-COOH}) can donate a proton (acting as an acid). Therefore, the correct answer is D: both an acid and a base.