Input interpretation
L-tryptophan | molar mass
Result
Find the molar mass, M, for L-tryptophan: M = sum _iN_im_i Plan: • Write the chemical formula and gather atomic masses from the periodic table. • Determine values for N_i and m_i using these items. • Finally, compute the mass. Write the chemical formula: C_11H_12N_2O_2 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i C (carbon) | 11 H (hydrogen) | 12 N (nitrogen) | 2 O (oxygen) | 2 Look up the atomic mass, m_i, in g·mol^(-1) for each element in the periodic table: | N_i | m_i/g·mol^(-1) C (carbon) | 11 | 12.011 H (hydrogen) | 12 | 1.008 N (nitrogen) | 2 | 14.007 O (oxygen) | 2 | 15.999 Multiply N_i by m_i to compute the mass for each element. Then sum those values to compute the molar mass, M: Answer: | | | N_i | m_i/g·mol^(-1) | mass/g·mol^(-1) C (carbon) | 11 | 12.011 | 11 × 12.011 = 132.121 H (hydrogen) | 12 | 1.008 | 12 × 1.008 = 12.096 N (nitrogen) | 2 | 14.007 | 2 × 14.007 = 28.014 O (oxygen) | 2 | 15.999 | 2 × 15.999 = 31.998 M = 132.121 g/mol + 12.096 g/mol + 28.014 g/mol + 31.998 g/mol = 204.229 g/mol
Unit conversion
0.20423 kg/mol (kilograms per mole)
Comparisons
≈ 0.28 × molar mass of fullerene ( ≈ 721 g/mol )
≈ 1.1 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 3.5 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 3.4×10^-22 grams | 3.4×10^-25 kg (kilograms) | 204 u (unified atomic mass units) | 204 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 204