Input interpretation
butyllithium | molar mass
Result
Find the molar mass, M, for butyllithium: 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: CH_3(CH_2)_3Li Use the chemical formula to count the number of atoms, N_i, for each element: | number of atoms C (carbon) | 4 H (hydrogen) | 9 Li (lithium) | 1 Look up the atomic mass, m_i, in g·mol^(-1) for each element in the periodic table: | number of atoms | atomic mass/g·mol^(-1) C (carbon) | 4 | 12.011 H (hydrogen) | 9 | 1.008 Li (lithium) | 1 | 6.94 Multiply N_i by m_i to compute the mass for each element. Then sum those values to compute the molar mass, M: Answer: | | | number of atoms | atomic mass/g·mol^(-1) | mass/g·mol^(-1) C (carbon) | 4 | 12.011 | 4 × 12.011 = 48.044 H (hydrogen) | 9 | 1.008 | 9 × 1.008 = 9.072 Li (lithium) | 1 | 6.94 | 1 × 6.94 = 6.94 M = 48.044 g/mol + 9.072 g/mol + 6.94 g/mol = 64.06 g/mol
Unit conversion
0.06406 kg/mol (kilograms per mole)
Comparisons
≈ ( 0.089 ≈ 1/11 ) × molar mass of fullerene (≈ 721 g/mol )
≈ 0.33 × molar mass of caffeine (≈ 194 g/mol )
≈ 1.1 × molar mass of sodium chloride (≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 1.1×10^-22 grams | 1.1×10^-25 kg (kilograms) | 64 u (unified atomic mass units) | 64 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 64