Question

How do I find the number of iron (Fe) atoms in 20 grams of ferric sulfate (Fe2(SO4)3)?

Answer 1

To find the number of iron (Fe) atoms in 20 grams of ferric sulfate (Fe2(SO4)3), you'll need to follow these steps:

1. Determine the molar mass of ferric sulfate (Fe2(SO4)3). You can find the atomic masses of iron (Fe), sulfur (S), and oxygen (O) from the periodic table. The molar mass is calculated by adding up the atomic masses of all the atoms in the compound.

Fe: 55.845 g/mol S: 32.06 g/mol O: 16.00 g/mol

Molar mass of ferric sulfate (Fe2(SO4)3): 2(Fe) + 3(S) + 12(O) = (2 * 55.845) + (3 * 32.06) + (12 * 16.00) = 399.71 g/mol

2. Calculate the number of moles of ferric sulfate in 20 grams using the formula:

Number of moles = Mass (g) / Molar mass (g/mol)

Number of moles = 20 g / 399.71 g/mol = 0.0501 mol (rounded to four decimal places)

3. Use the stoichiometry of the compound to determine the number of moles of iron (Fe) present. From the chemical formula Fe2(SO4)3, you can see that each formula unit contains 2 iron atoms.

Number of moles of iron (Fe) = 2 * Number of moles of ferric sulfate

Number of moles of iron (Fe) = 2 * 0.0501 mol = 0.1002 mol (rounded to four decimal places)

4. Finally, use Avogadro's number, which is approximately 6.022 x 10^23 atoms/mol, to calculate the number of iron (Fe) atoms:

Number of iron (Fe) atoms = Number of moles of iron (Fe) * Avogadro's number

Number of iron (Fe) atoms = 0.1002 mol * 6.022 x 10^23 atoms/mol = 6.026 x 10^22 atoms (rounded to three significant figures)

Therefore, there are approximately 6.026 x 10^22 iron (Fe) atoms in 20 grams of ferric sulfate (Fe2(SO4)3).