What is the change in enthalpy for the following reaction? 2h2o2(aq) 2h2o(l) + o2(g) given: h2o: ∆h= -242 kj h2o2: ∆h= -609 kj

Answer : The reaction will be .

Now as the given enthalpy of  is -242 KJ
and the enthalpy of is -609 KJ.

According to the formula of Hess's summation, ΔHreaction= (ΣΔHproducts)-(ΣΔHreactants)

Therefore, ΔHreaction = [ + ] -

on substituting the values and omitting the value for oxygen as it is in gaseous state we get,
ΔHreaction = [0 + (2 X -242)] - [2 X -609] 

on solving we get, ΔHreaction = 734 KJ.

Qrepresents joules in the formula