Hydrogen peroxide decomposes according to the following thermochemical reaction: H2O2(l) → H2O(l) + 1/2 O2(g); ΔH = -98.2 kJ Calculate the change in enthalpy, ΔH, when 1.00 g of hydrogen peroxide decomposes.

Dear sachin,

The thermochemical equation tells us that ΔH for the decomposition of 1 mole of H₂O₂ is -98.2 kJ, so this relationship can be used as a conversion factor. Using the Periodic table, the molecular mass of H₂O₂ is 34.0, which means that 1 mol H₂O₂ = 34.0 g H₂O₂.

Using these values:

ΔH = 1.00 g H₂O₂ x 1 mol H₂O₂ / 34.0 g H₂O₂ x -98.2 kJ / 1 mol H₂O₂

ΔH = -2.89 kJ

Please feel free to ask your queries here. We are all IITians and here to help you in your IIT JEE preparation.

All the best.

Win exciting gifts by answering the questions on Discussion Forum. So help discuss any query on askiitians forum and become an Elite Expert League askiitian.

Now you score 5+15 POINTS by uploading your Pic and Downloading the Askiitians Toolbar  respectively : Click here to download the toolbar..

Askiitians Expert

Sagar Singh

B.Tech, IIT Delhi

Approved