Input interpretation
strontium ferrocyanide pentadecahydrate | molar mass
Result
Find the molar mass, M, for strontium ferrocyanide pentadecahydrate: 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: SrFe(CN)_6·15H_2O Use the chemical formula, SrFe(CN)_6·15H_2O, to count the number of atoms, N_i, for each element: | N_i C (carbon) | 6 Fe (iron) | 1 H (hydrogen) | 30 N (nitrogen) | 6 O (oxygen) | 15 Sr (strontium) | 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) | 6 | 12.011 Fe (iron) | 1 | 55.845 H (hydrogen) | 30 | 1.008 N (nitrogen) | 6 | 14.007 O (oxygen) | 15 | 15.999 Sr (strontium) | 2 | 87.62 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) | 6 | 12.011 | 6 × 12.011 = 72.066 Fe (iron) | 1 | 55.845 | 1 × 55.845 = 55.845 H (hydrogen) | 30 | 1.008 | 30 × 1.008 = 30.240 N (nitrogen) | 6 | 14.007 | 6 × 14.007 = 84.042 O (oxygen) | 15 | 15.999 | 15 × 15.999 = 239.985 Sr (strontium) | 2 | 87.62 | 2 × 87.62 = 175.24 M = 72.066 g/mol + 55.845 g/mol + 30.240 g/mol + 84.042 g/mol + 239.985 g/mol + 175.24 g/mol = 657.42 g/mol
Unit conversion
0.6574 kg/mol (kilograms per mole)
Comparisons
≈ 0.91 × molar mass of fullerene ( ≈ 721 g/mol )
≈ 3.4 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 11 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 1.1×10^-21 grams | 1.1×10^-24 kg (kilograms) | 657 u (unified atomic mass units) | 657 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 657