Why does a CO2 reaction with barium peroxide give H2O2?

Because barium peroxide is a salt of hydrogen peroxide. When you add CO2, it forms carbonic acid which reacts with the barium cations to give barium carbonate, releasing hydrogen peroxide (the acid form of peroxide ions) into solution. read more

In the textbook of Sarda/Handa/Arora$^1$ this process with $\ce{CO2}$ is shortly mentioned (without any explanations except that ice-cold water should be used, and that $\ce{BaCO3}$ may be removed by filtration, since the desired product is, of course, $\ce{H2O2}$). read more

Concentrated Hydrogen Peroxide can also be used as an oxidant with organic compounds, such as kerosene, in a bipropellant rocket engine. The German V2 Rocket of WWII used this design. We will leverage the (Eq. 3Hydrogen Peroxide decomposition reaction ) to determine the concentration of Hydrogen Peroxide in products typically sold in the supermarket. read more