Acid Rain: The Nitric Acid Connection

How does nitrogen dioxide contribute to the acidity in rainwater?

Deduce an equation to show the reaction of nitrogen dioxide with oxygen and water to form nitric acid.

Answer:

Nitrogen dioxide (NO2) reacts with water and oxygen in the atmosphere to form nitric acid (HNO3), which contributes to acid rain.

Acid rain is a result of various pollutants released into the atmosphere, including nitrogen dioxide (NO2). This nitrogen compound plays a significant role in the formation of nitric acid (HNO3) in rainwater, increasing its acidity.

The chemical reaction for the formation of nitric acid from nitrogen dioxide, oxygen, and water vapor can be represented by the equation:

3NO2(g) + H2O(l) + ½O2(g) → 2HNO3(aq) + NO(g)

This equation illustrates that three molecules of nitrogen dioxide react with one molecule of water and half a molecule of oxygen to produce two molecules of nitric acid and one molecule of nitric oxide. This process contributes to the acidity in rainwater, leading to acid rain.

The reaction typically occurs in the atmosphere where nitrogen dioxide, a byproduct of combustion processes from vehicles and industrial activities, interacts with oxygen and water vapor to form nitric acid. This highlights the connection between nitrogen dioxide and the acidity in rainwater, emphasizing the role it plays in the formation of acid rain.