Question

How do you equate heat of reaction to heat of formation?

Write the balanced chemical reaction whose `DeltaH _"rxn" = DeltaH_f`

Answer 1

See below.

Explanation:

The heat of reaction `Δ_text(r)H` is the heat involved when a reaction takes place.

If the reaction involves the formation of a compound from its elements in the standard states, the heat of reaction is also called the heat of formation `Δ_text(f)H` of the compound.

As an example, for the reaction

`"2H"_2"(g)" + "O"_2"(g)" → 2"H"_2"O(l)", Δ_text(r)H = "-285.8 kJ· mol"^"-1"`

This reaction involves the formation of a compound from its elements, so the heat involved is also `Δ_text(f)H`.

For a reaction in which a compound is formed from its elements,

`Δ_text(r)H = Δ_text(f)H`