Input interpretation
![carbon tetrachloride | elemental composition](../image_source/296eed01eb737dd877e8b27745ec61bd.png)
carbon tetrachloride | elemental composition
Result
![Find the elemental composition for carbon tetrachloride 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: CCl_4 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) | 1 Cl (chlorine) | 4 N_atoms = 1 + 4 = 5 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) | 1 | 1/5 Cl (chlorine) | 4 | 4/5 Check: 1/5 + 4/5 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent C (carbon) | 1 | 1/5 × 100% = 20.0% Cl (chlorine) | 4 | 4/5 × 100% = 80.0% 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) | 1 | 20.0% | 12.011 Cl (chlorine) | 4 | 80.0% | 35.45 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) | 1 | 20.0% | 12.011 | 1 × 12.011 = 12.011 Cl (chlorine) | 4 | 80.0% | 35.45 | 4 × 35.45 = 141.80 m = 12.011 u + 141.80 u = 153.811 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) | 1 | 20.0% | 12.011/153.811 Cl (chlorine) | 4 | 80.0% | 141.80/153.811 Check: 12.011/153.811 + 141.80/153.811 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent C (carbon) | 1 | 20.0% | 12.011/153.811 × 100% = 7.809% Cl (chlorine) | 4 | 80.0% | 141.80/153.811 × 100% = 92.19%](../image_source/875df0b2605264c5a10c0eda03ce3e39.png)
Find the elemental composition for carbon tetrachloride 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: CCl_4 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) | 1 Cl (chlorine) | 4 N_atoms = 1 + 4 = 5 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) | 1 | 1/5 Cl (chlorine) | 4 | 4/5 Check: 1/5 + 4/5 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent C (carbon) | 1 | 1/5 × 100% = 20.0% Cl (chlorine) | 4 | 4/5 × 100% = 80.0% 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) | 1 | 20.0% | 12.011 Cl (chlorine) | 4 | 80.0% | 35.45 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) | 1 | 20.0% | 12.011 | 1 × 12.011 = 12.011 Cl (chlorine) | 4 | 80.0% | 35.45 | 4 × 35.45 = 141.80 m = 12.011 u + 141.80 u = 153.811 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) | 1 | 20.0% | 12.011/153.811 Cl (chlorine) | 4 | 80.0% | 141.80/153.811 Check: 12.011/153.811 + 141.80/153.811 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent C (carbon) | 1 | 20.0% | 12.011/153.811 × 100% = 7.809% Cl (chlorine) | 4 | 80.0% | 141.80/153.811 × 100% = 92.19%
Mass fraction pie chart
![Mass fraction pie chart](../image_source/3a9c2420db8ba7ca77a106f816f5841b.png)
Mass fraction pie chart