Input interpretation
magnesium phosphide | molar mass
Result
Find the molar mass, M, for magnesium phosphide: 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: Mg_3P_2 Use the chemical formula to count the number of atoms, N_i, for each element: | number of atoms Mg (magnesium) | 3 P (phosphorus) | 2 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) Mg (magnesium) | 3 | 24.305 P (phosphorus) | 2 | 30.973761998 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) Mg (magnesium) | 3 | 24.305 | 3 × 24.305 = 72.915 P (phosphorus) | 2 | 30.973761998 | 2 × 30.973761998 = 61.947523996 M = 72.915 g/mol + 61.947523996 g/mol = 134.863 g/mol
Unit conversion
0.13486 kg/mol (kilograms per mole)
Comparisons
≈ ( 0.19 ≈ 1/5 ) × molar mass of fullerene (≈ 721 g/mol )
≈ 0.69 × molar mass of caffeine (≈ 194 g/mol )
≈ 2.3 × molar mass of sodium chloride (≈ 58 g/mol )
Corresponding quantities
Mass of a molecule m from m = M/N_A: | 2.2×10^-22 grams | 2.2×10^-25 kg (kilograms) | 135 u (unified atomic mass units) | 135 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 135