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