Input interpretation
tin(II) iodide | relative molecular mass
Result
Find the relative molecular mass, M_r, for tin(II) iodide: M_r = sum _iN_im_i/m_u 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: SnI_2 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i I (iodine) | 2 Sn (tin) | 1 Look up the atomic mass, m_i, in unified atomic mass units, u, for each element in the periodic table. Since m_i is divided by the atomic mass constant, m_u, the result is a unitless relative atomic mass: | N_i | m_i/m_u I (iodine) | 2 | 126.90447 Sn (tin) | 1 | 118.710 Multiply N_i by m_i/m_u to compute the relative mass for each element. Then sum those values to compute the relative molecular mass, M_r: Answer: | | | N_i | m_i/m_u | relative mass I (iodine) | 2 | 126.90447 | 2 × 126.90447 = 253.80894 Sn (tin) | 1 | 118.710 | 1 × 118.710 = 118.710 M_r = 253.80894 + 118.710 = 372.519
Comparisons
≈ 0.52 × relative molecular mass of fullerene ( ≈ 721 )
≈ 1.9 × relative molecular mass of caffeine ( ≈ 194 )
≈ 6.4 × relative molecular mass of sodium chloride ( ≈ 58 )
Corresponding quantities
Molar mass M from M = M_uM_r: | 373 g/mol (grams per mole)
Molecular mass m from m = M_rM_u/N_A: | 6.2×10^-22 grams | 6.2×10^-25 kg (kilograms)