Input interpretation
erbium bromide hexahydrate | molar mass
Result
Find the molar mass, M, for erbium bromide hexahydrate: 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: ErBr_3·6H_2O Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Br (bromine) | 3 Er (erbium) | 1 H (hydrogen) | 12 O (oxygen) | 6 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) Br (bromine) | 3 | 79.904 Er (erbium) | 1 | 167.259 H (hydrogen) | 12 | 1.008 O (oxygen) | 6 | 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) Br (bromine) | 3 | 79.904 | 3 × 79.904 = 239.712 Er (erbium) | 1 | 167.259 | 1 × 167.259 = 167.259 H (hydrogen) | 12 | 1.008 | 12 × 1.008 = 12.096 O (oxygen) | 6 | 15.999 | 6 × 15.999 = 95.994 M = 239.712 g/mol + 167.259 g/mol + 12.096 g/mol + 95.994 g/mol = 515.061 g/mol
Unit conversion
0.51506 kg/mol (kilograms per mole)
Comparisons
≈ 0.71 × molar mass of fullerene ( ≈ 721 g/mol )
≈ 2.7 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 8.8 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 8.6×10^-22 grams | 8.6×10^-25 kg (kilograms) | 515 u (unified atomic mass units) | 515 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 515