How to Determine the Limiting Reagent:

To determine the limiting reagent in a chemical reaction, you need to compare the stoichiometry of the reactants and their amounts given in the question. The limiting reagent is the reactant that is completely consumed, thus limiting the amount of products that can be formed.

Given Question:
2Al + 6HCl → 2AlCl3 + 3H2

The question provides the following amounts of reactants:
- 5 moles of aluminum (Al)
- 10 moles of hydrochloric acid (HCl)

Step 1: Write and Balance the Chemical Equation:
Write the balanced chemical equation for the given reaction, making sure that the number of atoms on each side is equal.

2Al + 6HCl → 2AlCl3 + 3H2

Step 2: Determine the Stoichiometry:
Identify the stoichiometric ratio between the reactants and products from the balanced equation. This ratio tells you how many moles of each reactant are needed to produce a certain number of moles of products.

In this case, 2 moles of Al react with 6 moles of HCl to produce 2 moles of AlCl3 and 3 moles of H2.

Step 3: Calculate the Mole Ratio:
To compare the amounts of reactants given in the question, calculate the mole ratio of the given amounts to the stoichiometric ratio.

Given:
- 5 moles of Al
- 10 moles of HCl

Mole ratios:
- Al: 5/2 = 2.5
- HCl: 10/6 = 1.67

Step 4: Identify the Limiting Reagent:
The reactant with the smaller mole ratio is the limiting reagent because it will be completely consumed, preventing the reaction from proceeding further. In this case, HCl has a smaller mole ratio of 1.67, making it the limiting reagent.

Conclusion:
In the given question, HCl is the limiting reagent. This means that after the reaction is complete, there will be an excess of Al remaining. The amount of AlCl3 and H2 produced will be determined by the amount of HCl available, and the amount of Al will not be completely utilized.