Final answer:
The correct answer is option 1. At equilibrium for the given reaction, the concentration of HCl must be less than the concentration of Cl₂, but we cannot confidently say that [O₂] will be greater than [HCl] or that [Cl₂] must equal [H₂O], without additional information. Therefore, the only statement we can be sure about is the first one.
Step-by-step explanation:
The student's question pertains to the equilibrium situation of the chemical reaction 4HCl + O₂(g) ⇌ 2Cl₂ + 2H₂O (g). At equilibrium, we need to evaluate three statements based on the balanced chemical equation and the provided initial condition that equal moles of HCl and O₂ are present at the start.
Considering the balanced equation, for every 4 moles of HCl reacted, 2 moles of Cl₂ are produced, and similarly, for every 1 mole of O₂ reacted, 2 moles of H₂O are produced. This indicates that if both HCl and O₂ were present initially in equal amounts and all HCl were to react, there would be twice as many moles of Cl₂ produced as there are moles of H₂O because Cl₂ is produced from HCl on a 1:2 basis. Therefore, we can deduce that the concentration of Cl₂ would be equal to the concentration of H₂O at equilibrium as per statement 3, provided that all the HCl reacts, which is likely but not guaranteed. Without more information, we cannot assert if all the HCl reacts.
To address the statements:
- (HCl) must be less than [Cl₂]:
- [O₂] must be greater than [HCl]:
- (Cl₂) must equal [H₂O]: This is potentially true if all HCl reacts, due to the stoichiometry of the balanced equation, but is not guaranteed.
Considering this information, the only statement we can be sure about is the first one, since the reaction must have converted some of the HCl to Cl₂. Therefore, the answer would be (c) 1 only.