element mass fraction of fluorine perchlorate

fluorine perchlorate | elemental composition

Find the elemental composition for fluorine perchlorate 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: FOClO_3 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 Cl (chlorine) | 1 F (fluorine) | 1 H (hydrogen) | 1 O (oxygen) | 4 N_atoms = 1 + 1 + 1 + 4 = 7 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 Cl (chlorine) | 1 | 1/7 F (fluorine) | 1 | 1/7 H (hydrogen) | 1 | 1/7 O (oxygen) | 4 | 4/7 Check: 1/7 + 1/7 + 1/7 + 4/7 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent Cl (chlorine) | 1 | 1/7 × 100% = 14.3% F (fluorine) | 1 | 1/7 × 100% = 14.3% H (hydrogen) | 1 | 1/7 × 100% = 14.3% O (oxygen) | 4 | 4/7 × 100% = 57.1% 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 Cl (chlorine) | 1 | 14.3% | 35.45 F (fluorine) | 1 | 14.3% | 18.998403163 H (hydrogen) | 1 | 14.3% | 1.008 O (oxygen) | 4 | 57.1% | 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 Cl (chlorine) | 1 | 14.3% | 35.45 | 1 × 35.45 = 35.45 F (fluorine) | 1 | 14.3% | 18.998403163 | 1 × 18.998403163 = 18.998403163 H (hydrogen) | 1 | 14.3% | 1.008 | 1 × 1.008 = 1.008 O (oxygen) | 4 | 57.1% | 15.999 | 4 × 15.999 = 63.996 m = 35.45 u + 18.998403163 u + 1.008 u + 63.996 u = 119.452403163 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 Cl (chlorine) | 1 | 14.3% | 35.45/119.452403163 F (fluorine) | 1 | 14.3% | 18.998403163/119.452403163 H (hydrogen) | 1 | 14.3% | 1.008/119.452403163 O (oxygen) | 4 | 57.1% | 63.996/119.452403163 Check: 35.45/119.452403163 + 18.998403163/119.452403163 + 1.008/119.452403163 + 63.996/119.452403163 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent Cl (chlorine) | 1 | 14.3% | 35.45/119.452403163 × 100% = 29.68% F (fluorine) | 1 | 14.3% | 18.998403163/119.452403163 × 100% = 15.90% H (hydrogen) | 1 | 14.3% | 1.008/119.452403163 × 100% = 0.8439% O (oxygen) | 4 | 57.1% | 63.996/119.452403163 × 100% = 53.57%

Mass fraction pie chart