Calculate the standard reaction enthalpy for the reaction no2(g) → no(g) + o(g) given +142.7 kj/mol for the standard enthalpy of formation of ozone and o2(g) → 2 o(g) ∆h ◦ = +498.4 kj/mol no(g) + o3(g) → no2(g) + o2(g) ∆h◦ = −200 kj/mol remember the definition of the standard enthalpy of formation of a substance.

The standard reaction enthalpy for the given reaction is 235.15 kJ/mol.

Explanation:

..[1]

..[2]

..[3]

..[4]

Using Hess's law:

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

2 × [4] = [2]- (3 ) × [1] - (2) × [3]

The standard reaction enthalpy for the given reaction is 235.15 kJ/mol.