Input interpretation
![lithium selenide | molar mass](../image_source/1e41af3cb64d47e75284fab7b07e705b.png)
lithium selenide | molar mass
Result
![Find the molar mass, M, for lithium selenide: 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_2Se Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Li (lithium) | 2 Se (selenium) | 1 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) Li (lithium) | 2 | 6.94 Se (selenium) | 1 | 78.971 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) Li (lithium) | 2 | 6.94 | 2 × 6.94 = 13.88 Se (selenium) | 1 | 78.971 | 1 × 78.971 = 78.971 M = 13.88 g/mol + 78.971 g/mol = 92.85 g/mol](../image_source/79d472616d03f127f8bf8c0bafca0930.png)
Find the molar mass, M, for lithium selenide: 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_2Se Use the chemical formula to count the number of atoms, N_i, for each element: | N_i Li (lithium) | 2 Se (selenium) | 1 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) Li (lithium) | 2 | 6.94 Se (selenium) | 1 | 78.971 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) Li (lithium) | 2 | 6.94 | 2 × 6.94 = 13.88 Se (selenium) | 1 | 78.971 | 1 × 78.971 = 78.971 M = 13.88 g/mol + 78.971 g/mol = 92.85 g/mol
Unit conversion
![0.0929 kg/mol (kilograms per mole)](../image_source/7ebe78205e43f993fcc626141b6c2e61.png)
0.0929 kg/mol (kilograms per mole)
Comparisons
![≈ ( 0.13 ≈ 1/8 ) × molar mass of fullerene ( ≈ 721 g/mol )](../image_source/a4312ac3d3a347e3ad978c77b9e4a23b.png)
≈ ( 0.13 ≈ 1/8 ) × molar mass of fullerene ( ≈ 721 g/mol )
![≈ 0.48 × molar mass of caffeine ( ≈ 194 g/mol )](../image_source/0c8a38930ba7dfe9548248a33f443f4d.png)
≈ 0.48 × molar mass of caffeine ( ≈ 194 g/mol )
![≈ 1.6 × molar mass of sodium chloride ( ≈ 58 g/mol )](../image_source/64a7c18fc45d6992429f4d98cecd92a1.png)
≈ 1.6 × molar mass of sodium chloride ( ≈ 58 g/mol )
Corresponding quantities
![Mass of a molecule m from m = M/N_A: | 1.5×10^-22 grams | 1.5×10^-25 kg (kilograms) | 93 u (unified atomic mass units) | 93 Da (daltons)](../image_source/4ef0b5ab827720fcd202f43a40e0c763.png)
Mass of a molecule m from m = M/N_A: | 1.5×10^-22 grams | 1.5×10^-25 kg (kilograms) | 93 u (unified atomic mass units) | 93 Da (daltons)
![Relative molecular mass M_r from M_r = M_u/M: | 93](../image_source/08d9dbe303e13f35233d8b9cae57b5e0.png)
Relative molecular mass M_r from M_r = M_u/M: | 93