Oxygen cоmpоunds оf nitrogen contribute to аir pollution, sometimes in а very visible wаy, Shown below is a chemical reaction that converts nitrogen tetroxide, N2O4, into nitrogen dioxide, NO2, a reaction that can occur in the atmosphere. N2O4 is colorless, but NO2 has a brown color, and its presence in the atmosphere contributes to the "pollution haze" observed in some cities. Is this reaction spontaneous at 25°C? K = °C + 273 ΔG = ΔH - TΔS