Input interpretation
sodium iodide dihydrate | molar mass
Result
Find the molar mass, M, for sodium iodide dihydrate: 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: NaI·2H_2O Use the chemical formula, NaI·2H_2O, to count the number of atoms, N_i, for each element: | N_i H (hydrogen) | 2 I (iodine) | 1 Na (sodium) | 1 O (oxygen) | 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) H (hydrogen) | 2 | 1.008 I (iodine) | 1 | 126.90447 Na (sodium) | 1 | 22.98976928 O (oxygen) | 1 | 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) H (hydrogen) | 2 | 1.008 | 2 × 1.008 = 2.016 I (iodine) | 1 | 126.90447 | 1 × 126.90447 = 126.90447 Na (sodium) | 1 | 22.98976928 | 1 × 22.98976928 = 22.98976928 O (oxygen) | 1 | 15.999 | 1 × 15.999 = 15.999 M = 2.016 g/mol + 126.90447 g/mol + 22.98976928 g/mol + 15.999 g/mol = 167.909 g/mol
Unit conversion
0.167909 kg/mol (kilograms per mole)
Comparisons
≈ ( 0.23 ≈ 1/4 ) × molar mass of fullerene ( ≈ 721 g/mol )
≈ 0.86 × 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: | 2.8×10^-22 grams | 2.8×10^-25 kg (kilograms) | 168 u (unified atomic mass units) | 168 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 168