Input interpretation
lithium iodide | molar mass
Result
Find the molar mass, M, for lithium iodide: 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: LiI Use the chemical formula to count the number of atoms, N_i, for each element: | N_i I (iodine) | 1 Li (lithium) | 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) I (iodine) | 1 | 126.90447 Li (lithium) | 1 | 6.94 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) I (iodine) | 1 | 126.90447 | 1 × 126.90447 = 126.90447 Li (lithium) | 1 | 6.94 | 1 × 6.94 = 6.94 M = 126.90447 g/mol + 6.94 g/mol = 133.84 g/mol
Unit conversion
0.1338 kg/mol (kilograms per mole)
Comparisons
≈ ( 0.19 ≈ 1/5 ) × molar mass of fullerene ( ≈ 721 g/mol )
≈ 0.69 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 2.3 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 2.2×10^-22 grams | 2.2×10^-25 kg (kilograms) | 134 u (unified atomic mass units) | 134 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 134