Since the question is incomplete, here I copy the full question:
Consider the following reaction:
- 2NO (g) + 5 H₂ → 2 NH₃ (g) + 2H₂O (g)
A reaction mixture contains 5 moles of NO and 10 moles of H₂. Without doing any calculations, determine which of the following best represents the mixture after the reactants have reacted as completely as possible. Explain your reasoning.
a) 1 mol NO, 0 mol H₂, 4 mol NH₃, 4 mol H₂O
b) 0 mol NO, 1 mol H₂, 5 mol NH₃, 5 mol H₂O
c) 0 mol NO, 0 mol H₂, 4 mol NH₃, 4 mol H₂O
d) 3 mol NO, 5 mol H₂, 2 mol NH₃, 2 mol H₂O
Answer:
- <em><u>a) 1 mol NO, 0 mol H₂, 4 mol NH₃, 4 mol H₂O.</u></em>
Explanation:
The coefficients of the balanced chemical equation gives the stoichiometric mole ratios; this is, the proportion of the number of moles of each reactant that indeed react and the number of moles that can be yielded of each product .
Thus, from the balanced chemical equation, the mole ratios are:
- 2 mol NO (g) : 5 mol H₂ : 2 mol NH₃ (g) : 2 mol H₂O (g)
Now, the starting mixture contains 5 moles of NO and 10 moles of H₂, so:
- Looking at the reactant side, focus on the number of moles of H₂: you start with 10 moles, which is the double of 5 (the stoichiometric coefficient on the chemical equation), meaning that it will be needed the double of 2 moles of NO, i.e. 4 moles. Since, there more than 4 moles of NO (5), NO is in excess and H₂ is the limiting reactant. Then, when the 10 moles of H₂ have reacted, 4 moles of NO will have reacted and 1 mol of NO will remain (in excess).
Summarizing: after the reaction, there will be 1 mol NO and 0 mol H₂.
- Now let's look at the product side: the number of moles produced of each substance will be the double of what the stoichiometric coefficientes indicate, i.e. 4 mol NH₃ and 4 mol H₂O.
At the end, you have determined, without calculations, that <em>the mixture after the reactants have reacted as completely as possible, is represented </em>by the first option:
- a. 1 mol NO, 0 mol H₂, 4 mol NH₃, 4 mol H₂O.