# Problem: Consider the decomposition of liquid hydrogen peroxide (H2O2) to form water and oxygen.What is the heat of formation for gaseous oxygen?

###### FREE Expert Solution

We’re being asked to determine the standard enthalpy change of formation (ΔH˚f) for oxygen. Recall that ΔH˚rxn can be calculated from the enthalpy of formation (ΔH˚f) of the reactants and products involved

$\overline{){\mathbf{∆}}{\mathbf{H}}{{\mathbf{°}}}_{{\mathbf{rxn}}}{\mathbf{=}}{\mathbf{∆}}{\mathbf{H}}{{\mathbf{°}}}_{\mathbf{f}\mathbf{,}\mathbf{products}}{\mathbf{-}}{\mathbf{∆}}{\mathbf{H}}{{\mathbf{°}}}_{\mathbf{f}\mathbf{,}\mathbf{reactants}}}$

The chemical equation for the reaction is:

H2O2(l)→ O2(g) + H2O(l)

This equation is not yet balanced. To balance it, we have to make sure that the number of elements on both sides is equal.

Balance O: We have 2 O on the reactant side and 3 O on the product side – add a coefficient of 2 to H2O:

H2O2(l)→ O2(g)2 H2O(l)

Balance H: We have 2 H on the reactant side and 4 H on the product side – add a coefficient of 2 to O2:

2 H2O2(l)→ O2(g)2 H2O(l)

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###### Problem Details

Consider the decomposition of liquid hydrogen peroxide (H2O2) to form water and oxygen.

What is the heat of formation for gaseous oxygen?