A sample of an amino acid (M = 225.2 g.mol^-1) contains 1.56 g of C, 0.333 g of H, 2.08 g of O, and 0.910 g of N.

What are the empirical and molecular formulas of this amino acid?

Question

A sample of an amino acid (M = 225.2 g.mol^-1) contains 1.56 g of C, 0.333 g of H, 2.08 g of O, and 0.910 g of N.

What are the empirical and molecular formulas of this amino acid?

| General Chemistry 1

Accepted Answer

Empirical Formula:

Determine the number of atoms for each element:

n_C = m_C / M_C = 0.130 mol

n_H = m_H / M_H = 0.330 mol

n_O = 0.130 mol

n_N = 0.0650 mol

⇒ n_N= 2n_C = 2n_O = 5n_H

The empirical formula of this amino acid is: C₂H₅O₂N

Molecular Formula:

The molar mass of C₂H₅O₂Nis 75.05 g.mol^-1

The molar mass of this amino acid is 225.2 g.mol^-1

225.2/75.05 = 3, the molecular formula of vitamin C is C₆H₁₅O₆N₃

Midterm 1 - Question 2 | General Chemistry 1