molar mass of phosphotungstic acid hydrate

phosphotungstic acid hydrate | molar mass

Find the molar mass, M, for phosphotungstic acid hydrate: 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: H_3[P(W_3O_10)_4]·xH_2O Use the chemical formula to count the number of atoms, N_i, for each element: | N_i H (hydrogen) | 5 O (oxygen) | 41 P (phosphorus) | 1 W (tungsten) | 12 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) H (hydrogen) | 5 | 1.008 O (oxygen) | 41 | 15.999 P (phosphorus) | 1 | 30.973761998 W (tungsten) | 12 | 183.84 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) H (hydrogen) | 5 | 1.008 | 5 × 1.008 = 5.040 O (oxygen) | 41 | 15.999 | 41 × 15.999 = 655.959 P (phosphorus) | 1 | 30.973761998 | 1 × 30.973761998 = 30.973761998 W (tungsten) | 12 | 183.84 | 12 × 183.84 = 2206.08 M = 5.040 g/mol + 655.959 g/mol + 30.973761998 g/mol + 2206.08 g/mol = 2898.05 g/mol

2.8981 kg/mol (kilograms per mole)

≈ 4 × molar mass of fullerene ( ≈ 721 g/mol )

≈ 15 × molar mass of caffeine ( ≈ 194 g/mol )

≈ 50 × molar mass of sodium chloride ( ≈ 58 g/mol )

Mass of a molecule m from m = M/N_A: | 4.8×10^-21 grams | 4.8×10^-24 kg (kilograms) | 2898 u (unified atomic mass units) | 2.9 kDa (kilodaltons)

Relative molecular mass M_r from M_r = M_u/M: | 2898