Input interpretation
rubidium iodide | molar mass
Result
Find the molar mass, M, for rubidium 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: RbI Use the chemical formula, RbI, to count the number of atoms, N_i, for each element: | N_i I (iodine) | 1 Rb (rubidium) | 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 Rb (rubidium) | 1 | 85.4678 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 Rb (rubidium) | 1 | 85.4678 | 1 × 85.4678 = 85.4678 M = 126.90447 g/mol + 85.4678 g/mol = 212.3723 g/mol
Unit conversion
0.212372 kg/mol (kilograms per mole)
Comparisons
≈ 0.29 × molar mass of fullerene ( ≈ 721 g/mol )
≈ 1.1 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 3.6 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 3.5×10^-22 grams | 3.5×10^-25 kg (kilograms) | 212 u (unified atomic mass units) | 212 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 212