Input interpretation
ammonium persulfate | molecular mass
Result
Find the molecular mass, m, for ammonium persulfate: 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: (NH_4)_2S_2O_8 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i H (hydrogen) | 8 N (nitrogen) | 2 O (oxygen) | 8 S (sulfur) | 2 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 H (hydrogen) | 8 | 1.008 N (nitrogen) | 2 | 14.007 O (oxygen) | 8 | 15.999 S (sulfur) | 2 | 32.06 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 H (hydrogen) | 8 | 1.008 | 8 × 1.008 = 8.064 N (nitrogen) | 2 | 14.007 | 2 × 14.007 = 28.014 O (oxygen) | 8 | 15.999 | 8 × 15.999 = 127.992 S (sulfur) | 2 | 32.06 | 2 × 32.06 = 64.12 m = 8.064 u + 28.014 u + 127.992 u + 64.12 u = 228.19 u
Unit conversions
228.2 Da (daltons)
0.2282 kDa (kilodaltons)
3.789×10^-22 grams
3.789×10^-25 kg (kilograms)
228.2 chemical atomic mass units (unit officially deprecated)
228.3 physical atomic mass units (unit officially deprecated)
Comparisons as mass of molecule
≈ 0.32 × molecular mass of fullerene ( ≈ 721 u )
≈ 1.2 × molecular mass of caffeine ( ≈ 194 u )
≈ 3.9 × molecular mass of sodium chloride ( ≈ 58 u )
Corresponding quantities
Relative atomic mass A_r from A_r = m_aN_A/M_u: | 228
Molar mass M from M = m_aN_A: | 228 g/mol (grams per mole)
Relative molecular mass M_r from M_r = m_mN_A/M_u: | 228
Molar mass M from M = m_mN_A: | 228 g/mol (grams per mole)