mass fractions of aluminum-nickel catalyst

aluminum-nickel catalyst | elemental composition

Find the elemental composition for aluminum-nickel catalyst 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: AlNi Use the chemical formula, AlNi, to count the number of atoms, N_i, for each element and find the total number of atoms, N_atoms: | number of atoms Al (aluminum) | 1 Ni (nickel) | 1 N_atoms = 1 + 1 = 2 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 Al (aluminum) | 1 | 1/2 Ni (nickel) | 1 | 1/2 Check: 1/2 + 1/2 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent Al (aluminum) | 1 | 1/2 × 100% = 50.0% Ni (nickel) | 1 | 1/2 × 100% = 50.0% 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 Al (aluminum) | 1 | 50.0% | 26.9815385 Ni (nickel) | 1 | 50.0% | 58.6934 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 Al (aluminum) | 1 | 50.0% | 26.9815385 | 1 × 26.9815385 = 26.9815385 Ni (nickel) | 1 | 50.0% | 58.6934 | 1 × 58.6934 = 58.6934 m = 26.9815385 u + 58.6934 u = 85.6749385 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 Al (aluminum) | 1 | 50.0% | 26.9815385/85.6749385 Ni (nickel) | 1 | 50.0% | 58.6934/85.6749385 Check: 26.9815385/85.6749385 + 58.6934/85.6749385 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent Al (aluminum) | 1 | 50.0% | 26.9815385/85.6749385 × 100% = 31.49% Ni (nickel) | 1 | 50.0% | 58.6934/85.6749385 × 100% = 68.51%

Mass fraction pie chart