How much heat will be released if 2.55grams of Hydrogen Peroxide (H2O2) decomposes in a bombardier beetle to produce a steam spray?

Question

2H2O2 ----> 2H2O + O2 ΔHrxn = -190.0 kJ.

Answer 1

We use dimensional analysis to problem using the molecular weight of Hydrogen Peroxide (34 g), our initial weight, and the amount of hear released in the exothermic reaction(-190 kJ).

2.55 g H₂O₂ x 1 mol H₂O₂ /34 g H₂O₂ x -190 kJ/ 2 mol H₂O₂ = 7.13 kJ