A highly purified sample of of an unknown, neutral -amino acid reacted quantitatively with nitrous a — Biomolecules Chemistry Question
Question
A highly purified sample of $0.89\text{ g}$ of an unknown, neutral $\alpha$ -amino acid reacted quantitatively with nitrous acid ($HNO_2$) at STP, releasing exactly $224\text{ mL}$ of $N_2$ gas. Identify the unknown amino acid based on this stoichiometric data. (Given molar masses: Glycine=75, Alanine=89, Valine=117)
Answer: B
💡 Solution & Explanation
Primary aliphatic amines react with $HNO_2$ to release 1 mole of $N_2$ per mole of amine. Moles of $N_2 = \frac{0.224\text{ L}}{22.4\text{ L/mol}} = 0.01\text{ mol}$. This means there is $0.01\text{ mol}$ of the amino acid. Molar mass = $\frac{0.89\text{ g}}{0.01\text{ mol}} = 89\text{ g/mol}$, which matches the molar mass of Alanine.
💬Ask on WhatsApp →
Still have doubts about this question?
Send it to our AI chemistry tutor on WhatsApp — gets answered in minutes