Answer:
- What is the limiting reactant?: HCl is the limitng reactant.
- How many moles of H₂ are formed?: 6.5 moles of H₂ are formed.
Step-by-step explanation:
Part A: what is the limiting reactant?
1) Balanced chemical equation: given
- 2Al + 6HCl → 2AlCl₃ + 3H₂
2) Stoichiometric mole ratio:
Use the coefficients of the balanced equation:
- 2 mol Al : 6 mol HCl : 2 mol AlCl₃ : 3H₂
3) Compare the stoichiometric mole ratio of the reactants with their actual ratio:
- Theoretical ratio: 2 mol Al / 6 mol HCl ≈ 0.33 mol Al / mol HCl
- Actual ratio: 6.0 mol Al / 13 mol Cl ≈ 0.46 mol Al / mol Cl
Since the actual ratio indicates that there is a greater number of moles of Al (0.46) per mol of Cl than what is required by the stoichiometric ratio(0.33), Al is in excess and HCl is the limiting reactant.
Answer: the limiting reactant is HCl.
Part B. How many moles of H₂ are formed?
3. Determine how many moles of H₂ can be formed
- Theoretical ratio using limiting reactant:
6 mol HCl / 3 mol H₂ = 13 mol HCl / x
⇒ x = 13 mol HCl × 3 mol H₂ / 6 mol HCl = 6.5 mol H₂.
The answer must be reported with two significant digits, such as the data are given.
Answer: 6.5 moles of H₂ are formed