Chemistry 5070 · O Level · The mole and the Avogadro constant

The mole and the Avogadro constant — practice question

Aqueous hydrogen peroxide, $\text{H}_2\text{O}_2$, breaks down slowly at $25^\circ\text{C}$. $2\text{H}_2\text{O}_2(aq) \rightarrow 2\text{H}_2\text{O}(l) + \text{O}_2(g)$ When a catalyst is introduced, this decomposition occurs more quickly. A student adds a small quantity of catalyst to $10\,\text{cm}^3$ of $1.0\,\text{mol dm}^{-3}$ $\text{H}_2\text{O}_2(aq)$ and then collects the gas produced. The collected gas has a volume of $90\,\text{cm}^3$. All measurements are taken at room temperature and pressure. What is the percentage yield of $\text{O}_2(g)$?

  • A28.1%
  • B37.5%
  • C56.3%
  • D75.0%

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