element tally of calcium nitride

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calcium nitride | elemental composition

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$Find the elemental composition for calcium nitride 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: Ca_3N_2 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 Ca (calcium) | 3 N (nitrogen) | 2 N_atoms = 3 + 2 = 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 Ca (calcium) | 3 | 3/5 N (nitrogen) | 2 | 2/5 Check: 3/5 + 2/5 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent Ca (calcium) | 3 | 3/5 × 100% = 60.0% N (nitrogen) | 2 | 2/5 × 100% = 40.0% 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 Ca (calcium) | 3 | 60.0% | 40.078 N (nitrogen) | 2 | 40.0% | 14.007 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 Ca (calcium) | 3 | 60.0% | 40.078 | 3 × 40.078 = 120.234 N (nitrogen) | 2 | 40.0% | 14.007 | 2 × 14.007 = 28.014 m = 120.234 u + 28.014 u = 148.248 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 Ca (calcium) | 3 | 60.0% | 120.234/148.248 N (nitrogen) | 2 | 40.0% | 28.014/148.248 Check: 120.234/148.248 + 28.014/148.248 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent Ca (calcium) | 3 | 60.0% | 120.234/148.248 × 100% = 81.10% N (nitrogen) | 2 | 40.0% | 28.014/148.248 × 100% = 18.90%$

Find the elemental composition for calcium nitride 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: Ca_3N_2 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 Ca (calcium) | 3 N (nitrogen) | 2 N_atoms = 3 + 2 = 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 Ca (calcium) | 3 | 3/5 N (nitrogen) | 2 | 2/5 Check: 3/5 + 2/5 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent Ca (calcium) | 3 | 3/5 × 100% = 60.0% N (nitrogen) | 2 | 2/5 × 100% = 40.0% 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 Ca (calcium) | 3 | 60.0% | 40.078 N (nitrogen) | 2 | 40.0% | 14.007 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 Ca (calcium) | 3 | 60.0% | 40.078 | 3 × 40.078 = 120.234 N (nitrogen) | 2 | 40.0% | 14.007 | 2 × 14.007 = 28.014 m = 120.234 u + 28.014 u = 148.248 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 Ca (calcium) | 3 | 60.0% | 120.234/148.248 N (nitrogen) | 2 | 40.0% | 28.014/148.248 Check: 120.234/148.248 + 28.014/148.248 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent Ca (calcium) | 3 | 60.0% | 120.234/148.248 × 100% = 81.10% N (nitrogen) | 2 | 40.0% | 28.014/148.248 × 100% = 18.90%