Input interpretation
copper(II) niobate | relative molecular mass
Result
Find the relative molecular mass, M_r, for copper(II) niobate: M_r = sum _iN_im_i/m_u 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: Cu(NbO_3)_2 Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Cu (copper) | 1 Nb (niobium) | 2 O (oxygen) | 6 Look up the atomic mass, m_i, in unified atomic mass units, u, for each element in the periodic table. Since m_i is divided by the atomic mass constant, m_u, the result is a unitless relative atomic mass: | N_i | m_i/m_u Cu (copper) | 1 | 63.546 Nb (niobium) | 2 | 92.90637 O (oxygen) | 6 | 15.999 Multiply N_i by m_i/m_u to compute the relative mass for each element. Then sum those values to compute the relative molecular mass, M_r: Answer: | | | N_i | m_i/m_u | relative mass Cu (copper) | 1 | 63.546 | 1 × 63.546 = 63.546 Nb (niobium) | 2 | 92.90637 | 2 × 92.90637 = 185.81274 O (oxygen) | 6 | 15.999 | 6 × 15.999 = 95.994 M_r = 63.546 + 185.81274 + 95.994 = 345.353
Comparisons
≈ 0.48 × relative molecular mass of fullerene ( ≈ 721 )
≈ 1.8 × relative molecular mass of caffeine ( ≈ 194 )
≈ 5.9 × relative molecular mass of sodium chloride ( ≈ 58 )
Corresponding quantities
Molar mass M from M = M_uM_r: | 345 g/mol (grams per mole)
Molecular mass m from m = M_rM_u/N_A: | 5.7×10^-22 grams | 5.7×10^-25 kg (kilograms)