Input interpretation
erythromycin stearate | molar mass
Result
Find the molar mass, M, for erythromycin stearate: 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_55H_103NO_15 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i C (carbon) | 55 H (hydrogen) | 103 N (nitrogen) | 1 O (oxygen) | 15 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) | 55 | 12.011 H (hydrogen) | 103 | 1.008 N (nitrogen) | 1 | 14.007 O (oxygen) | 15 | 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) | 55 | 12.011 | 55 × 12.011 = 660.605 H (hydrogen) | 103 | 1.008 | 103 × 1.008 = 103.824 N (nitrogen) | 1 | 14.007 | 1 × 14.007 = 14.007 O (oxygen) | 15 | 15.999 | 15 × 15.999 = 239.985 M = 660.605 g/mol + 103.824 g/mol + 14.007 g/mol + 239.985 g/mol = 1018.421 g/mol
Unit conversion
1.0184 kg/mol (kilograms per mole)
Comparisons
≈ 1.4 × molar mass of fullerene ( ≈ 721 g/mol )
≈ 5.2 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 17 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 1.7×10^-21 grams | 1.7×10^-24 kg (kilograms) | 1018 u (unified atomic mass units) | 1 kDa (kilodalton)
Relative molecular mass M_r from M_r = M_u/M: | 1018