mass fractions of tungsten(IV) chloride

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tungsten(IV) chloride | elemental composition

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$Find the elemental composition for tungsten(IV) chloride 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: WCl_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 Cl (chlorine) | 4 W (tungsten) | 1 N_atoms = 4 + 1 = 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 Cl (chlorine) | 4 | 4/5 W (tungsten) | 1 | 1/5 Check: 4/5 + 1/5 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent Cl (chlorine) | 4 | 4/5 × 100% = 80.0% W (tungsten) | 1 | 1/5 × 100% = 20.0% 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 Cl (chlorine) | 4 | 80.0% | 35.45 W (tungsten) | 1 | 20.0% | 183.84 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) | 4 | 80.0% | 35.45 | 4 × 35.45 = 141.80 W (tungsten) | 1 | 20.0% | 183.84 | 1 × 183.84 = 183.84 m = 141.80 u + 183.84 u = 325.64 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) | 4 | 80.0% | 141.80/325.64 W (tungsten) | 1 | 20.0% | 183.84/325.64 Check: 141.80/325.64 + 183.84/325.64 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent Cl (chlorine) | 4 | 80.0% | 141.80/325.64 × 100% = 43.55% W (tungsten) | 1 | 20.0% | 183.84/325.64 × 100% = 56.45%$

Find the elemental composition for tungsten(IV) chloride 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: WCl_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 Cl (chlorine) | 4 W (tungsten) | 1 N_atoms = 4 + 1 = 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 Cl (chlorine) | 4 | 4/5 W (tungsten) | 1 | 1/5 Check: 4/5 + 1/5 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent Cl (chlorine) | 4 | 4/5 × 100% = 80.0% W (tungsten) | 1 | 1/5 × 100% = 20.0% 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 Cl (chlorine) | 4 | 80.0% | 35.45 W (tungsten) | 1 | 20.0% | 183.84 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) | 4 | 80.0% | 35.45 | 4 × 35.45 = 141.80 W (tungsten) | 1 | 20.0% | 183.84 | 1 × 183.84 = 183.84 m = 141.80 u + 183.84 u = 325.64 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) | 4 | 80.0% | 141.80/325.64 W (tungsten) | 1 | 20.0% | 183.84/325.64 Check: 141.80/325.64 + 183.84/325.64 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent Cl (chlorine) | 4 | 80.0% | 141.80/325.64 × 100% = 43.55% W (tungsten) | 1 | 20.0% | 183.84/325.64 × 100% = 56.45%