Input interpretation
iron(II) phosphate octahydrate | molar mass
Result
Find the molar mass, M, for iron(II) phosphate octahydrate: 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: Fe_3(PO_4)_2·8H_2O Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Fe (iron) | 3 H (hydrogen) | 16 O (oxygen) | 16 P (phosphorus) | 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) Fe (iron) | 3 | 55.845 H (hydrogen) | 16 | 1.008 O (oxygen) | 16 | 15.999 P (phosphorus) | 2 | 30.973761998 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) Fe (iron) | 3 | 55.845 | 3 × 55.845 = 167.535 H (hydrogen) | 16 | 1.008 | 16 × 1.008 = 16.128 O (oxygen) | 16 | 15.999 | 16 × 15.999 = 255.984 P (phosphorus) | 2 | 30.973761998 | 2 × 30.973761998 = 61.947523996 M = 167.535 g/mol + 16.128 g/mol + 255.984 g/mol + 61.947523996 g/mol = 501.595 g/mol
Unit conversion
0.50159 kg/mol (kilograms per mole)
Comparisons
≈ 0.7 × molar mass of fullerene ( ≈ 721 g/mol )
≈ 2.6 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 8.6 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 8.3×10^-22 grams | 8.3×10^-25 kg (kilograms) | 502 u (unified atomic mass units) | 502 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 502