element tally of fmoc-(4-iodo)-phe-OH

fmoc-(4-iodo)-phe-OH | elemental composition

Find the elemental composition for fmoc-(4-iodo)-phe-OH 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_24H_20INO_4 Use the chemical formula, C_24H_20INO_4, 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) | 24 H (hydrogen) | 20 I (iodine) | 1 N (nitrogen) | 1 O (oxygen) | 4 N_atoms = 24 + 20 + 1 + 1 + 4 = 50 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) | 24 | 24/50 H (hydrogen) | 20 | 20/50 I (iodine) | 1 | 1/50 N (nitrogen) | 1 | 1/50 O (oxygen) | 4 | 4/50 Check: 24/50 + 20/50 + 1/50 + 1/50 + 4/50 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent C (carbon) | 24 | 24/50 × 100% = 48.0% H (hydrogen) | 20 | 20/50 × 100% = 40.0% I (iodine) | 1 | 1/50 × 100% = 2.00% N (nitrogen) | 1 | 1/50 × 100% = 2.00% O (oxygen) | 4 | 4/50 × 100% = 8.00% 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) | 24 | 48.0% | 12.011 H (hydrogen) | 20 | 40.0% | 1.008 I (iodine) | 1 | 2.00% | 126.90447 N (nitrogen) | 1 | 2.00% | 14.007 O (oxygen) | 4 | 8.00% | 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) | 24 | 48.0% | 12.011 | 24 × 12.011 = 288.264 H (hydrogen) | 20 | 40.0% | 1.008 | 20 × 1.008 = 20.160 I (iodine) | 1 | 2.00% | 126.90447 | 1 × 126.90447 = 126.90447 N (nitrogen) | 1 | 2.00% | 14.007 | 1 × 14.007 = 14.007 O (oxygen) | 4 | 8.00% | 15.999 | 4 × 15.999 = 63.996 m = 288.264 u + 20.160 u + 126.90447 u + 14.007 u + 63.996 u = 513.33147 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) | 24 | 48.0% | 288.264/513.33147 H (hydrogen) | 20 | 40.0% | 20.160/513.33147 I (iodine) | 1 | 2.00% | 126.90447/513.33147 N (nitrogen) | 1 | 2.00% | 14.007/513.33147 O (oxygen) | 4 | 8.00% | 63.996/513.33147 Check: 288.264/513.33147 + 20.160/513.33147 + 126.90447/513.33147 + 14.007/513.33147 + 63.996/513.33147 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent C (carbon) | 24 | 48.0% | 288.264/513.33147 × 100% = 56.16% H (hydrogen) | 20 | 40.0% | 20.160/513.33147 × 100% = 3.927% I (iodine) | 1 | 2.00% | 126.90447/513.33147 × 100% = 24.72% N (nitrogen) | 1 | 2.00% | 14.007/513.33147 × 100% = 2.729% O (oxygen) | 4 | 8.00% | 63.996/513.33147 × 100% = 12.47%

Mass fraction pie chart