Input interpretation
aluminum selenide | molar mass
Result
Find the molar mass, M, for aluminum selenide: 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_2Se_3 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Al (aluminum) | 2 Se (selenium) | 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) | 2 | 26.9815385 Se (selenium) | 3 | 78.971 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) | 2 | 26.9815385 | 2 × 26.9815385 = 53.9630770 Se (selenium) | 3 | 78.971 | 3 × 78.971 = 236.913 M = 53.9630770 g/mol + 236.913 g/mol = 290.876 g/mol
Unit conversion
0.29088 kg/mol (kilograms per mole)
Comparisons
≈ 0.4 × molar mass of fullerene ( ≈ 721 g/mol )
≈ 1.5 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 5 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 4.8×10^-22 grams | 4.8×10^-25 kg (kilograms) | 291 u (unified atomic mass units) | 291 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 291