How many grams of iron are created?

Question

1) How many grams of iron are created from 50 moles of FeO?

2Al + 3FeO --> 3Fe + Al2O3

2) How many grams of iron are created from 59 grams of Al?

2Al + 3FeO --> 3Fe + Al2O3

Answer 1

Hello, Vanishree,

1. The balanced equation tells us that we'll get 3 moles of Fe for every 3 moles of FeO we put in, assuming there is sufficient Al. That's a molar ratio of 1/1 or 1. That means if we react all 50 moles of FeO, we should get 50 moles of Fe. Convert 50 moles of Fe into grams by multiplying by the molar mass of iron, which is 55.88 grams/mole. I arrive at 2792 grams, but this number should be rounded to the correct sig figs. 50 moles, without the decimal point, only has 1 sig fig. It was too painful for me to round my hard-won 2792 grams, so I'll leave it to you to report 3000 grams. I can't.
2. The molar ratio of Fe to Al is 3/2. We'll get 1.5 times the moles of Fe as we use of Al. Find the moles of Al by dividing by it's molar mass, 26.98 g/mole. Assuming we have sufficient FeO, all 2.19 moles of Al will react to form (1.5)*(2.19 moles) = 3.28 moles of Fe. Multiply by iron's molar mass to find grams. I get 183 grams. 183 grams with 3 sig figs.

Bob