Question

Liquid hydrogen peroxide, an oxidizing agent in many rocket fuel mixtures, releases oxygen gas on decomposition: 2 h2o2(l) → 2 h2o(l) + o2(g) δhrxn = −196.1 kj calculate the heat for the decomposition of 785 kg of h2o2

Answer 1

Answer : To calculate the heat of decomposition for the reaction,

$2H _{2} O_{2} ----\ \textgreater \ 2H_{2} O + O_{2}$, in this reaction there are two moles of peroxide reacting to give 2 moles of water and 1 mole of oxygen.

Also the given weight of peroxide is 785 kg which we need to convert into moles. Molecular weight of peroxide is approximately 34 g/ mol.

So in moles the mol wt of peroxide will be, 785 (1000g/1Kg) X (1 mol/34 g) = 23088.2 mol

Therefore now on solving we get,

23088.2 mol of peroxide X (-196.1 KJ/2 mol of peroxide) = -2263798.01  KJ o heat.

Hence, the heat of decomposition will be -2263798.01  KJ.