Input interpretation
sodium bichromate | molar mass
Result
Find the molar mass, M, for sodium bichromate: 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: Na_2Cr_2O_7 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Cr (chromium) | 2 Na (sodium) | 2 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) Cr (chromium) | 2 | 51.9961 Na (sodium) | 2 | 22.98976928 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) Cr (chromium) | 2 | 51.9961 | 2 × 51.9961 = 103.9922 Na (sodium) | 2 | 22.98976928 | 2 × 22.98976928 = 45.97953856 O (oxygen) | 7 | 15.999 | 7 × 15.999 = 111.993 M = 103.9922 g/mol + 45.97953856 g/mol + 111.993 g/mol = 261.965 g/mol
Unit conversion
0.26196 kg/mol (kilograms per mole)
Comparisons
≈ 0.36 × molar mass of fullerene ( ≈ 721 g/mol )
≈ 1.3 × molar mass of caffeine ( ≈ 194 g/mol )
≈ 4.5 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 4.4×10^-22 grams | 4.4×10^-25 kg (kilograms) | 262 u (unified atomic mass units) | 262 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 262