Exactly of a hydrogen peroxide solution with a concentration of completely decomposes to yield water — Hydrogen Chemistry Question

💡 Solution & Explanation

The concentration is $34\text{ g L}^{-1}$. In $200\text{ mL}$ ($0.2\text{ L}$), the mass of $H_2O_2$ is $34 \times 0.2 = 6.8\text{ grams}$. The decomposition reaction is $2H_2O_2 \rightarrow 2H_2O + O_2$. The molar mass of $H_2O_2$ is $34\text{ g mol}^{-1}$. Two moles ($68\text{ g}$) of $H_2O_2$ yield one mole ($32\text{ g}$) of $O_2$. Thus, $6.8\text{ g}$ of $H_2O_2$ will yield $(32 / 68) \times 6.8 = 3.2\text{ grams}$ of $O_2$.