Input interpretation
aluminum hydroxide | molar mass
Result
Find the molar mass, M, for aluminum hydroxide: 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: Al(OH)_3 Use the chemical formula, Al(OH)_3, to count the number of atoms, N_i, for each element: | N_i Al (aluminum) | 1 H (hydrogen) | 3 O (oxygen) | 3 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) Al (aluminum) | 1 | 26.9815385 H (hydrogen) | 3 | 1.008 O (oxygen) | 3 | 15.999 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) Al (aluminum) | 1 | 26.9815385 | 1 × 26.9815385 = 26.9815385 H (hydrogen) | 3 | 1.008 | 3 × 1.008 = 3.024 O (oxygen) | 3 | 15.999 | 3 × 15.999 = 47.997 M = 26.9815385 g/mol + 3.024 g/mol + 47.997 g/mol = 78.003 g/mol
Unit conversion
0.078003 kg/mol (kilograms per mole)
Comparisons
≈ ( 0.11 ≈ 1/9 ) × molar mass of fullerene ( ≈ 721 g/mol )
≈ 0.4 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 1.3 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 1.3×10^-22 grams | 1.3×10^-25 kg (kilograms) | 78 u (unified atomic mass units) | 78 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 78