Chapter 14

Q. 14.2.2

For the decomposition of hydrogen peroxide in dilute sodium hydroxide at 20 °C,
2 H_{2}O_{2}(aq) → 2 H_{2}O(ℓ) + O_{2}(g)
the average rate of disappearance of H_{2}O_{2} over the period from t = 0 to t = 516 min is found to be 8.08 × 10^{-5} M/min. What is the rate of appearance of O_{2} over the same period?


Verified Solution

You are asked to calculate the rate of appearance of a product in a chemical reaction.
You are given a balanced equation for a chemical reaction and the rate of disappearance of a reactant.
The reaction stoichiometry shows that two moles of H_{2}O_{2} are consumed for every mole of O_{2} formed. Therefore, the rate of formation of O_{2} is half the rate of H_{2}O_{2} consumption

\frac{\Delta \left[O_{2}\right] }{\Delta t}=-\frac{1}{2}\frac{\Delta \left[H_{2}O_{2}\right] }{\Delta t}=\frac{1}{2}\left(8.08\times 10^{-5}\text{ M/min}\right) =4.04\times 10^{-5} M/min