element mass fraction of boc-L-prolinal

boc-L-prolinal | elemental composition

Find the elemental composition for boc-L-prolinal 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_10H_17NO_3 Use the chemical formula, C_10H_17NO_3, 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) | 10 H (hydrogen) | 17 N (nitrogen) | 1 O (oxygen) | 3 N_atoms = 10 + 17 + 1 + 3 = 31 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) | 10 | 10/31 H (hydrogen) | 17 | 17/31 N (nitrogen) | 1 | 1/31 O (oxygen) | 3 | 3/31 Check: 10/31 + 17/31 + 1/31 + 3/31 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent C (carbon) | 10 | 10/31 × 100% = 32.3% H (hydrogen) | 17 | 17/31 × 100% = 54.8% N (nitrogen) | 1 | 1/31 × 100% = 3.23% O (oxygen) | 3 | 3/31 × 100% = 9.68% 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) | 10 | 32.3% | 12.011 H (hydrogen) | 17 | 54.8% | 1.008 N (nitrogen) | 1 | 3.23% | 14.007 O (oxygen) | 3 | 9.68% | 15.999 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) | 10 | 32.3% | 12.011 | 10 × 12.011 = 120.110 H (hydrogen) | 17 | 54.8% | 1.008 | 17 × 1.008 = 17.136 N (nitrogen) | 1 | 3.23% | 14.007 | 1 × 14.007 = 14.007 O (oxygen) | 3 | 9.68% | 15.999 | 3 × 15.999 = 47.997 m = 120.110 u + 17.136 u + 14.007 u + 47.997 u = 199.250 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) | 10 | 32.3% | 120.110/199.250 H (hydrogen) | 17 | 54.8% | 17.136/199.250 N (nitrogen) | 1 | 3.23% | 14.007/199.250 O (oxygen) | 3 | 9.68% | 47.997/199.250 Check: 120.110/199.250 + 17.136/199.250 + 14.007/199.250 + 47.997/199.250 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent C (carbon) | 10 | 32.3% | 120.110/199.250 × 100% = 60.28% H (hydrogen) | 17 | 54.8% | 17.136/199.250 × 100% = 8.600% N (nitrogen) | 1 | 3.23% | 14.007/199.250 × 100% = 7.030% O (oxygen) | 3 | 9.68% | 47.997/199.250 × 100% = 24.09%

Mass fraction pie chart