Consider the chemical equations shown here. Upper N Upper O (g) + Upper O Subscript 3 Baseline (g) right arrow Upper N Upper O Subscript 2 Baseline (g) + Upper O Subscript 2 Baseline (g) delta Upper H Subscript 1 Baseline = negative 198.9 kilojoules. StartFraction 3 Over 2 EndFraction Upper O Subscript 2 Baseline (g) right arrow Upper O Subscript 3 Baseline (g) delta Upper H Subscript 2 Baseline = 142.3 kilojoules. Upper O (g) right arrow one half Upper O Subscript 2 Baseline (g) delta Upper H Subscript 3 Baseline = negative 247.5 kilojoules.

What is Delta. Hrxn for the reaction shown below?

Upper n upper O (g) plus upper O (g) right arrow upper N upper O subscript 2 (g).