Input interpretation
phosphorus trichloride | molar mass
Result
Find the molar mass, M, for phosphorus trichloride: 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: PCl_3 Use the chemical formula to count the number of atoms, N_i, for each element: | number of atoms Cl (chlorine) | 3 P (phosphorus) | 1 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) Cl (chlorine) | 3 | 35.45 P (phosphorus) | 1 | 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) Cl (chlorine) | 3 | 35.45 | 3 × 35.45 = 106.35 P (phosphorus) | 1 | 30.973761998 | 1 × 30.973761998 = 30.973761998 M = 106.35 g/mol + 30.973761998 g/mol = 137.32 g/mol
Unit conversion
0.1373 kg/mol (kilograms per mole)
Comparisons
≈ ( 0.19 ≈ 1/5 ) × molar mass of fullerene (≈ 721 g/mol )
≈ 0.71 × 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: | 2.3×10^-22 grams | 2.3×10^-25 kg (kilograms) | 137 u (unified atomic mass units) | 137 Da (daltons)
Relative molecular mass M_r from M_r = M_u/M: | 137