How many grams of iron can be obtained from a 268 g sample of iron (III) oxide (Fe^2 O^3)?
To find the number of grams of iron that can be obtained from a sample of iron (III) oxide, we need to calculate the molar mass of Fe₂O₃ and then use stoichiometry to convert from moles of Fe₂O₃ to moles of iron (Fe), and finally to grams of iron.
Here's how you can do it step by step:
1. Find the molar mass of Fe₂O₃:
The molar mass of iron (Fe) is 55.845 g/mol, and the molar mass of oxygen (O) is 16.00 g/mol. Since Fe₂O₃ has two iron atoms and three oxygen atoms, the molar mass of Fe₂O₃ is calculated as follows:
Molar mass of Fe₂O₃ = (2 * molar mass of Fe) + (3 * molar mass of O)
= (2 * 55.845 g/mol) + (3 * 16.00 g/mol)
= 111.69 g/mol + 48.00 g/mol
= 159.69 g/mol
2. Calculate the number of moles of Fe₂O₃ in the given sample:
To find the number of moles, we can use the formula:
Moles of compound = Mass of the compound / Molar mass of the compound
Moles of Fe₂O₃ = 268 g / 159.69 g/mol
≈ 1.678 mol
3. Apply stoichiometry to convert moles of Fe₂O₃ to moles of Fe:
From the balanced chemical equation, we know that the ratio of moles of Fe to moles of Fe₂O₃ is 2:1 (Fe₂O₃ → Fe). Therefore, we need to multiply the moles of Fe₂O₃ by the stoichiometric factor (2) to get the moles of Fe.
Moles of Fe = Moles of Fe₂O₃ * (2 moles of Fe / 1 mole of Fe₂O₃)
= 1.678 mol * (2 mol Fe / 1 mol Fe₂O₃)
= 3.356 mol
4. Convert moles of Fe to grams of Fe:
To convert moles to grams, we can use the formula:
Mass = Moles * Molar mass
Mass of Fe = 3.356 mol * 55.845 g/mol
= 187.30 g
Therefore, approximately 187.30 grams of iron can be obtained from a 268 g sample of iron (III) oxide (Fe₂O₃).
Here is a worked example of a stoichiometry problem. Just follow the steps.
http://www.jiskha.com/science/chemistry/stoichiometry.html