mass fractions of chloramine t

chloramine t | elemental composition

Find the elemental composition for chloramine t 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: CH_3C_6H_4SO_2NClNa Use the chemical formula to count the number of atoms, N_i, for each element and find the total number of atoms, N_atoms, per molecule: | number of atoms C (carbon) | 7 Cl (chlorine) | 1 H (hydrogen) | 7 N (nitrogen) | 1 Na (sodium) | 1 O (oxygen) | 2 S (sulfur) | 1 N_atoms = 7 + 1 + 7 + 1 + 1 + 2 + 1 = 20 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) | 7 | 7/20 Cl (chlorine) | 1 | 1/20 H (hydrogen) | 7 | 7/20 N (nitrogen) | 1 | 1/20 Na (sodium) | 1 | 1/20 O (oxygen) | 2 | 2/20 S (sulfur) | 1 | 1/20 Check: 7/20 + 1/20 + 7/20 + 1/20 + 1/20 + 2/20 + 1/20 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent C (carbon) | 7 | 7/20 × 100% = 35.0% Cl (chlorine) | 1 | 1/20 × 100% = 5.00% H (hydrogen) | 7 | 7/20 × 100% = 35.0% N (nitrogen) | 1 | 1/20 × 100% = 5.00% Na (sodium) | 1 | 1/20 × 100% = 5.00% O (oxygen) | 2 | 2/20 × 100% = 10.00% S (sulfur) | 1 | 1/20 × 100% = 5.00% 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) | 7 | 35.0% | 12.011 Cl (chlorine) | 1 | 5.00% | 35.45 H (hydrogen) | 7 | 35.0% | 1.008 N (nitrogen) | 1 | 5.00% | 14.007 Na (sodium) | 1 | 5.00% | 22.98976928 O (oxygen) | 2 | 10.00% | 15.999 S (sulfur) | 1 | 5.00% | 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) | 7 | 35.0% | 12.011 | 7 × 12.011 = 84.077 Cl (chlorine) | 1 | 5.00% | 35.45 | 1 × 35.45 = 35.45 H (hydrogen) | 7 | 35.0% | 1.008 | 7 × 1.008 = 7.056 N (nitrogen) | 1 | 5.00% | 14.007 | 1 × 14.007 = 14.007 Na (sodium) | 1 | 5.00% | 22.98976928 | 1 × 22.98976928 = 22.98976928 O (oxygen) | 2 | 10.00% | 15.999 | 2 × 15.999 = 31.998 S (sulfur) | 1 | 5.00% | 32.06 | 1 × 32.06 = 32.06 m = 84.077 u + 35.45 u + 7.056 u + 14.007 u + 22.98976928 u + 31.998 u + 32.06 u = 227.63776928 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) | 7 | 35.0% | 84.077/227.63776928 Cl (chlorine) | 1 | 5.00% | 35.45/227.63776928 H (hydrogen) | 7 | 35.0% | 7.056/227.63776928 N (nitrogen) | 1 | 5.00% | 14.007/227.63776928 Na (sodium) | 1 | 5.00% | 22.98976928/227.63776928 O (oxygen) | 2 | 10.00% | 31.998/227.63776928 S (sulfur) | 1 | 5.00% | 32.06/227.63776928 Check: 84.077/227.63776928 + 35.45/227.63776928 + 7.056/227.63776928 + 14.007/227.63776928 + 22.98976928/227.63776928 + 31.998/227.63776928 + 32.06/227.63776928 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent C (carbon) | 7 | 35.0% | 84.077/227.63776928 × 100% = 36.93% Cl (chlorine) | 1 | 5.00% | 35.45/227.63776928 × 100% = 15.57% H (hydrogen) | 7 | 35.0% | 7.056/227.63776928 × 100% = 3.100% N (nitrogen) | 1 | 5.00% | 14.007/227.63776928 × 100% = 6.153% Na (sodium) | 1 | 5.00% | 22.98976928/227.63776928 × 100% = 10.10% O (oxygen) | 2 | 10.00% | 31.998/227.63776928 × 100% = 14.06% S (sulfur) | 1 | 5.00% | 32.06/227.63776928 × 100% = 14.08%

Mass fraction pie chart