The question
Name: ______________________ Date: ____________ Initial rates for hydrogen peroxide and iodide (4 points)
Data table
Initial rates at 25 °C
In acidic solution, hydrogen peroxide oxidizes iodide ions: H₂O₂(aq) + 2 I⁻(aq) + 2 H⁺(aq) → I₂(aq) + 2 H₂O(l). Initial rates of formation of I₂ were measured at 25 °C.
| Trial | [H₂O₂] (M) | [I⁻] (M) | [H⁺] (M) | Initial rate (M/s) |
|---|---|---|---|---|
| 1 | 0.10 | 0.10 | 0.10 | 1.20 × 10⁻⁴ |
| 2 | 0.20 | 0.10 | 0.10 | 2.40 × 10⁻⁴ |
| 3 | 0.10 | 0.30 | 0.10 | 3.60 × 10⁻⁴ |
| 4 | 0.10 | 0.10 | 0.20 | 1.20 × 10⁻⁴ |
(a) Determine the rate law for the reaction. [1 point]
(b) Calculate the value of the rate constant, k. Include units. [1 point]
(c) A student claims the reaction happens in one elementary step, exactly as the balanced equation is written. Explain why the data do not support this claim. [1 point]
(d) Trial 1 is repeated at 35 °C and the initial rate is larger. Explain this observation in terms of the collisions between reacting particles. [1 point]