Input interpretation
rubidium fluoride | molecular mass
Result
Find the molecular mass, m, for rubidium fluoride: 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: RbF Use the chemical formula, RbF, to count the number of atoms, N_i, for each element: | N_i F (fluorine) | 1 Rb (rubidium) | 1 Look up the atomic mass, m_i, in unified atomic mass units, u, for each element in the periodic table: | N_i | m_i/u F (fluorine) | 1 | 18.998403163 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 molecular mass, m: Answer: | | | N_i | m_i/u | mass/u F (fluorine) | 1 | 18.998403163 | 1 × 18.998403163 = 18.998403163 Rb (rubidium) | 1 | 85.4678 | 1 × 85.4678 = 85.4678 m = 18.998403163 u + 85.4678 u = 104.4662 u
Unit conversions
104.466 Da (daltons)
0.104466 kDa (kilodaltons)
1.7347×10^-22 grams
1.7347×10^-25 kg (kilograms)
104.471 chemical atomic mass units (unit officially deprecated)
104.499 physical atomic mass units (unit officially deprecated)
Comparisons as mass of molecule
≈ ( 0.14 ≈ 1/7 ) × molecular mass of fullerene ( ≈ 721 u )
≈ 0.54 × molecular mass of caffeine ( ≈ 194 u )
≈ 1.8 × molecular mass of sodium chloride ( ≈ 58 u )
Corresponding quantities
Relative atomic mass A_r from A_r = m_aN_A/M_u: | 104
Molar mass M from M = m_aN_A: | 104 g/mol (grams per mole)
Relative molecular mass M_r from M_r = m_mN_A/M_u: | 104
Molar mass M from M = m_mN_A: | 104 g/mol (grams per mole)