Question

Aluminum oxide and iron react according to the following equation: 4al2o3+9fe→ 3fe3o4+8al
If there are 10.2 grams of al2o3 and 11.2 grams of fe, which statement identifies the limiting reagent in this reaction and best supports that claim? (options below)

Answer 1

The equation is balanced (always check first)

Between Al2O3 and Fe, determine which makes less product. You can’t tell just by looking at the reaction coefficients, you have to determine how many moles of each you have.

Starting with 10.2g Al2O3, convert this to moles by dividing by the molar mass of Al2O3. Then divide by 4 moles since the reaction uses 4 moles Al2O3.

Repeat with Fe. Convert to moles by dividing by the molar mass of Fe. Then divide by 9 moles.

Whichever product gives you a smaller result is your limiting reactant.

Answer 2

This question is a bit tricky but the limiting reactant is determined by the actual quantity (mass) not simply the reaction coefficients.

Answer 3

Yes, I meant to update my progress.
So it's 0.200555107887904 mol Fe for 11.2 g of Fe. 0.10003797912454528 mol Al2O3 for 10.2 g of Al2O3. What I did was divide Fe by Al2O3 and compare it to the 9 Fe/4 Al2O3, which was 2.00 compared to 2.25 which got me confused as to which one made it smaller, so I'll try what you suggested.
Turned out Fe was indeed the lower number, so I got that much right at least. And based on your comment about it being determined by the mass, I'm gonna assume the answer is D.

Answer 4

(was correct)