if 15 grams of iron combines with 6.5 grams of oxygen, how much rust is formed
Since the final product is iron oxide (of several possible forms), with no gas release, all of the iron and oxygen mass ends up as rust.
the law of conservation of matter causes the theoretical yield of this reaction to be 21.5 grams of iron oxide.
To determine the amount of rust formed when 15 grams of iron combines with 6.5 grams of oxygen, we first need to understand the chemical reaction involved.
The chemical reaction between iron and oxygen forms iron(III) oxide, commonly known as rust. The balanced chemical equation for this reaction is:
4 Fe + 3 O2 → 2 Fe2O3
From the balanced equation, we can see that 4 moles of iron react with 3 moles of oxygen to produce 2 moles of iron(III) oxide.
Now, let's calculate the number of moles for iron and oxygen based on the given masses:
1. Calculate the number of moles of iron:
Number of moles = mass / molar mass
The molar mass of iron (Fe) is approximately 55.85 g/mol.
Number of moles of iron = 15 g / 55.85 g/mol ≈ 0.268 mol
2. Calculate the number of moles of oxygen:
The molar mass of oxygen (O2) is approximately 32 g/mol.
Number of moles of oxygen = 6.5 g / 32 g/mol ≈ 0.203 mol
Based on the balanced equation, we can see that the reaction uses 4 moles of iron for every 3 moles of oxygen.
Thus, the limiting reactant is oxygen because it has fewer moles compared to iron (0.203 mol < 0.268 mol).
To find the moles of rust formed, we compare the stoichiometry of iron(III) oxide in the balanced equation:
4 moles of iron will produce 2 moles of iron(III) oxide.
Now, let's find the moles of rust formed:
Moles of rust = (Number of moles of iron / 4) * 2
Moles of rust = (0.268 mol / 4) * 2 ≈ 0.134 mol
Finally, to convert moles of rust into grams, we multiply by the molar mass of iron(III) oxide (Fe2O3) which is approximately 159.69 g/mol:
Mass of rust = Moles of rust * molar mass
Mass of rust = 0.134 mol * 159.69 g/mol ≈ 21.40 g
Therefore, approximately 21.40 grams of rust would form when 15 grams of iron combines with 6.5 grams of oxygen.