Input interpretation
lithium carbonate | molar mass
Result
Find the molar mass, M, for lithium carbonate: 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: Li_2CO_3 Use the chemical formula to count the number of atoms, N_i, for each element: | number of atoms C (carbon) | 1 Li (lithium) | 2 O (oxygen) | 3 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) | 1 | 12.011 Li (lithium) | 2 | 6.94 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: | | | number of atoms | atomic mass/g·mol^(-1) | mass/g·mol^(-1) C (carbon) | 1 | 12.011 | 1 × 12.011 = 12.011 Li (lithium) | 2 | 6.94 | 2 × 6.94 = 13.88 O (oxygen) | 3 | 15.999 | 3 × 15.999 = 47.997 M = 12.011 g/mol + 13.88 g/mol + 47.997 g/mol = 73.89 g/mol
Unit conversion
0.0739 kg/mol (kilograms per mole)
Comparisons
≈ ( 0.1 ≈ 1/10 ) × molar mass of fullerene (≈ 721 g/mol )
≈ 0.38 × 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: | 1.2×10^-22 grams | 1.2×10^-25 kg (kilograms) | 74 u (unified atomic mass units) | 74 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 74