Question

Liquid hydrogen peroxide is an oxidizing agent in many rocket fuel mixtures because it releases oxygen gas on decomposition as shown below. 2 H202 (1) ► 2 H20,() + O2 (g) AHrxn = -196 kJ How much heat istreleased when 25.0 grams of H202 decomposes? Molar Mass(H2O2) = 34.01 g/mol Ca.-133 kJ b.-533 k] c-72.0 kj 0-288 kJ e-144 kJ

Answer 1

moles of H2O2 = mass/molar mass = 25/34.01 = 0.735 mol

From the given reaction

2H2O2(l) -------> 2H2O(l) +O2(g) , ∆Hrxn = -196KJ

2 mol of H2O2 released = -196 KJ heat

0.735 mll of H2O2 released = (-196/2)*0.735 = -72.03 or -72.0 KJ ......... Answer

So, option (iii) is correct.