Input interpretation
brushite | molar mass
Result
Find the molar mass, M, for brushite: 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: CaHPO_4·2H_2O Use the chemical formula, CaHPO_4·2H_2O, to count the number of atoms, N_i, for each element: | N_i Ca (calcium) | 1 H (hydrogen) | 5 O (oxygen) | 6 P (phosphorus) | 1 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) Ca (calcium) | 1 | 40.078 H (hydrogen) | 5 | 1.008 O (oxygen) | 6 | 15.999 P (phosphorus) | 1 | 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) Ca (calcium) | 1 | 40.078 | 1 × 40.078 = 40.078 H (hydrogen) | 5 | 1.008 | 5 × 1.008 = 5.040 O (oxygen) | 6 | 15.999 | 6 × 15.999 = 95.994 P (phosphorus) | 1 | 30.973761998 | 1 × 30.973761998 = 30.973761998 M = 40.078 g/mol + 5.040 g/mol + 95.994 g/mol + 30.973761998 g/mol = 172.086 g/mol
Unit conversion
0.17209 kg/mol (kilograms per mole)
Comparisons
≈ ( 0.24 ≈ 1/4 ) × molar mass of fullerene ( ≈ 721 g/mol )
≈ 0.89 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 2.9 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 2.9×10^-22 grams | 2.9×10^-25 kg (kilograms) | 172 u (unified atomic mass units) | 172 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 172