In a reaction, 114 grams of Al reacts with 186 grams of Cl2. What is the limiting reactant?
Al + Cl2 ----> AlCl3
first, balance the equation:
2Al + 3Cl2 → 2AlCl3
Now, how many moles of each reagent do you have?
114g Al = 4.225 moles
186g Cl2 = 2.657 moles
so, if all the Al is used up, you will need 4.225(3/2) = 6.338 moles of Cl2
You don't have that, so clearly the Cl2 limits the reaction
To find the limiting reactant, you need to compare the number of moles of Al and Cl2.
First, you need to convert the mass of each reactant to moles using the molar mass:
Molar mass of Al: 26.98 g/mol
Molar mass of Cl2: 35.45 g/mol (17.73 g/mol per Cl atom)
Moles of Al = mass of Al / molar mass of Al
= 114 g / 26.98 g/mol
= 4.224 mol
Moles of Cl2 = mass of Cl2 / molar mass of Cl2
= 186 g / 35.45 g/mol
= 5.238 mol
Next, you need to calculate the mole ratio of Al to Cl2 using the balanced equation:
Al + Cl2 -> AlCl3
From the equation, the ratio of Al to Cl2 is 1:1.
Comparing the mole ratio to the actual number of moles, we can see that there is an excess of Cl2:
Moles of Al: 4.224 mol
Moles of Cl2: 5.238 mol
In this case, the limiting reactant is Al because it is completely consumed in the reaction, whereas there is still excess Cl2 remaining.
To determine the limiting reactant, you need to compare the number of moles of each reactant in the given amounts. Here's how you can calculate it:
Step 1: Convert the given masses of Al and Cl2 to moles.
Molar mass of Al (Aluminum) = 26.98 g/mol
Molar mass of Cl2 (Chlorine) = 35.45 g/mol (one Cl atom)
Moles of Al = Mass of Al / Molar mass of Al
= 114 g / 26.98 g/mol
≈ 4.23 moles
Moles of Cl2 = Mass of Cl2 / Molar mass of Cl2
= 186 g / (35.45 g/mol * 2) (Multiply by 2 to account for 2 Cl atoms in one Cl2 molecule)
≈ 5.23 moles
Step 2: Use the balanced chemical equation to determine the stoichiometric ratio between Al and Cl2.
From the balanced equation: Al + Cl2 → AlCl3
The stoichiometric ratio of Al to Cl2 is 1:1.
Step 3: Compare the moles of Al and Cl2. The reactant with the lower number of moles is the limiting reactant.
In this case, Al has 4.23 moles, while Cl2 has 5.23 moles. The limiting reactant is the one with fewer moles, which is Al. Therefore, Al is the limiting reactant in this reaction.