Should 20 g of aluminium be mixed with 65 g of iron oxide and ignited, which substance will be the limiting reagent?
To determine the limiting reagent in a chemical reaction, we need to compare the moles of each reactant. The reactant that has fewer moles compared to what is required for the reaction will be the limiting reagent.
Let's start by finding the moles of each reactant:
1. Determine the molar mass of each substance:
- Aluminum (Al): 26.98 g/mol
- Iron oxide (Fe2O3): 159.69 g/mol
2. Use the molar mass to calculate the moles of each substance:
- Moles of aluminum (Al): 20 g / 26.98 g/mol ≈ 0.741 mol
- Moles of iron oxide (Fe2O3): 65 g / 159.69 g/mol ≈ 0.407 mol
Now, we need to compare the moles of each reactant to see which one is present in the lowest amount. In this case, the reactant with fewer moles is the limiting reagent.
From the calculations, we see that aluminum has more moles (0.741 mol) compared to iron oxide (0.407 mol). Therefore, iron oxide is the limiting reagent because it is present in the smallest amount, and after it is consumed completely, the reaction will stop.
So, in the given chemical reaction, the substance that will be the limiting reagent is iron oxide (Fe2O3).