To determine which two statements about the reaction are true, let's analyze a reaction graph depicting [tex]$2 H_2 O + O_2 \rightleftarrows 2 H_2 O_2$[/tex] as it reaches equilibrium.
### Statement Analysis:
Statement A: Equilibrium is first reached at point 2.
- In a reaction, equilibrium is reached when the rate of the forward reaction equals the rate of the reverse reaction, and the concentrations of reactants and products remain constant over time. At point 2, the graph should show no further significant change in concentration of products and reactants. This would indicate that equilibrium has been established.
Statement B: At point 1, the reaction proceeds mostly in the forward direction.
- At the beginning of the reaction (point 1), reactants ([tex]$H_2 O$[/tex] and [tex]$O_2$[/tex]) are at their initial concentrations. The reaction proceeds in the forward direction until it starts approaching equilibrium. Hence, at point 1, it is correct to say the reaction is proceeding mostly in the forward direction where more products ([tex]$H_2 O_2$[/tex]) are being formed.
Statement C: At point 3, the reactants and products reach their equilibrium concentrations.
- Once the reaction has reached equilibrium, the concentrations of the reactants and products remain constant. Thus, at point 3, the system has settled into its equilibrium state with stable concentrations of [tex]$H_2 O$[/tex], [tex]$O_2$[/tex], and [tex]$H_2 O_2$[/tex].
Statement D: After point 3, the reaction stops.
- When a reaction reaches equilibrium, it does not stop but continues with the forward and reverse reactions occurring at equal rates. So the concentrations of reactants and products remain unchanged, but the reaction itself does not stop.
From the analysis:
- True Statements:
- A. Equilibrium is first reached at point 2.
- C. At point 3, the reactants and products reach their equilibrium concentrations.
Therefore, the true statements about the reaction are A and C.
