element tally of fondaparinux sodium

fondaparinux sodium | elemental composition

Find the elemental composition for fondaparinux sodium in terms of the atom and mass percents: atom percent = N_i/N_atoms × 100% mass percent = (N_im_i)/m × 100% Plan: • Write the chemical formula and gather atomic masses from the periodic table. • Determine values for N_i, m_i, N_atoms and m using these items. • Finally, compute the percents and check the results. Write the chemical formula: C_31H_43N_3Na_10O_49S_8 Use the chemical formula, C_31H_43N_3Na_10O_49S_8, to count the number of atoms, N_i, for each element and find the total number of atoms, N_atoms: | number of atoms C (carbon) | 31 H (hydrogen) | 43 N (nitrogen) | 3 Na (sodium) | 10 O (oxygen) | 49 S (sulfur) | 8 N_atoms = 31 + 43 + 3 + 10 + 49 + 8 = 144 Divide each N_i by N_atoms to calculate atom fractions. Then use the property that atom fractions must sum to one to check the work: | number of atoms | atom fraction C (carbon) | 31 | 31/144 H (hydrogen) | 43 | 43/144 N (nitrogen) | 3 | 3/144 Na (sodium) | 10 | 10/144 O (oxygen) | 49 | 49/144 S (sulfur) | 8 | 8/144 Check: 31/144 + 43/144 + 3/144 + 10/144 + 49/144 + 8/144 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent C (carbon) | 31 | 31/144 × 100% = 21.5% H (hydrogen) | 43 | 43/144 × 100% = 29.9% N (nitrogen) | 3 | 3/144 × 100% = 2.08% Na (sodium) | 10 | 10/144 × 100% = 6.94% O (oxygen) | 49 | 49/144 × 100% = 34.0% S (sulfur) | 8 | 8/144 × 100% = 5.56% Look up the atomic mass, m_i, in unified atomic mass units, u, for each element in the periodic table: | number of atoms | atom percent | atomic mass/u C (carbon) | 31 | 21.5% | 12.011 H (hydrogen) | 43 | 29.9% | 1.008 N (nitrogen) | 3 | 2.08% | 14.007 Na (sodium) | 10 | 6.94% | 22.98976928 O (oxygen) | 49 | 34.0% | 15.999 S (sulfur) | 8 | 5.56% | 32.06 Multiply N_i by m_i to compute the mass for each element. Then sum those values to compute the molecular mass, m: | number of atoms | atom percent | atomic mass/u | mass/u C (carbon) | 31 | 21.5% | 12.011 | 31 × 12.011 = 372.341 H (hydrogen) | 43 | 29.9% | 1.008 | 43 × 1.008 = 43.344 N (nitrogen) | 3 | 2.08% | 14.007 | 3 × 14.007 = 42.021 Na (sodium) | 10 | 6.94% | 22.98976928 | 10 × 22.98976928 = 229.89769280 O (oxygen) | 49 | 34.0% | 15.999 | 49 × 15.999 = 783.951 S (sulfur) | 8 | 5.56% | 32.06 | 8 × 32.06 = 256.48 m = 372.341 u + 43.344 u + 42.021 u + 229.89769280 u + 783.951 u + 256.48 u = 1728.03469280 u Divide the mass for each element by m to calculate mass fractions. Then use the property that mass fractions must sum to one to check the work: | number of atoms | atom percent | mass fraction C (carbon) | 31 | 21.5% | 372.341/1728.03469280 H (hydrogen) | 43 | 29.9% | 43.344/1728.03469280 N (nitrogen) | 3 | 2.08% | 42.021/1728.03469280 Na (sodium) | 10 | 6.94% | 229.89769280/1728.03469280 O (oxygen) | 49 | 34.0% | 783.951/1728.03469280 S (sulfur) | 8 | 5.56% | 256.48/1728.03469280 Check: 372.341/1728.03469280 + 43.344/1728.03469280 + 42.021/1728.03469280 + 229.89769280/1728.03469280 + 783.951/1728.03469280 + 256.48/1728.03469280 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent C (carbon) | 31 | 21.5% | 372.341/1728.03469280 × 100% = 21.55% H (hydrogen) | 43 | 29.9% | 43.344/1728.03469280 × 100% = 2.508% N (nitrogen) | 3 | 2.08% | 42.021/1728.03469280 × 100% = 2.432% Na (sodium) | 10 | 6.94% | 229.89769280/1728.03469280 × 100% = 13.30% O (oxygen) | 49 | 34.0% | 783.951/1728.03469280 × 100% = 45.37% S (sulfur) | 8 | 5.56% | 256.48/1728.03469280 × 100% = 14.84%

Mass fraction pie chart