For this you must Cross multiply and cancel any two units that are the same and diagonal from each other.
I attached a screenshot of my work. Hopefully it all makes sense.
Answer:
1.3 mol H₂O
Explanation:
Let's consider the decomposition reaction of ammonium perchlorate.
NH₄ClO₄(s) → 1/2 N₂(g) + 1/2 Cl₂(g) + O₂(g) + 2 H₂O(g)
As we can see in the balanced equation, the molar ratio of ammonium perchlorate to water is 1:2. The moles of water produced by the reaction of 2.5 mol of ammonium perchlorate.
2.5 mol NH₄ClO₄ × (2 mol H₂O / 1 mol NH₄ClO₄) = 1.3 mol H₂O
Answer: 1.8 x 10^1 or the scientific e notation is: 1.8e1