Input interpretation
cerium(III) bromide heptahydrate | molar mass
Result
Find the molar mass, M, for cerium(III) bromide heptahydrate: 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: CeBr_3·7H_2O Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Br (bromine) | 3 Ce (cerium) | 1 H (hydrogen) | 14 O (oxygen) | 7 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) Br (bromine) | 3 | 79.904 Ce (cerium) | 1 | 140.116 H (hydrogen) | 14 | 1.008 O (oxygen) | 7 | 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) Br (bromine) | 3 | 79.904 | 3 × 79.904 = 239.712 Ce (cerium) | 1 | 140.116 | 1 × 140.116 = 140.116 H (hydrogen) | 14 | 1.008 | 14 × 1.008 = 14.112 O (oxygen) | 7 | 15.999 | 7 × 15.999 = 111.993 M = 239.712 g/mol + 140.116 g/mol + 14.112 g/mol + 111.993 g/mol = 505.933 g/mol
Unit conversion
0.50593 kg/mol (kilograms per mole)
Comparisons
≈ 0.7 × molar mass of fullerene ( ≈ 721 g/mol )
≈ 2.6 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 8.7 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 8.4×10^-22 grams | 8.4×10^-25 kg (kilograms) | 506 u (unified atomic mass units) | 506 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 506