Problem 29 - Chemistry: The Central Science in SI Units, Global Edition

Question

Nitrogen oxides like \(\mathrm{NO}_{2}\) and \(\mathrm{NO}\) are a significant source of acid rain. For each of these molecules write an equation that shows how an acid is formed from the reaction with water.

Step-by-Step Solution

Answer

The balanced chemical equations for the formation of acids from nitrogen oxides reacting with water are: 1. For NO₂: \(NO₂ (g) + H₂O (l) \rightarrow HNO₃ (aq) + HNO₂ (aq)\) 2. For NO: \(2NO (g) + 2H₂O (l) \rightarrow 2HNO₂ (aq) + NH₂OH (aq)\)

Step 1: Formation of nitric acid from NO₂

When nitrogen dioxide (NO₂) reacts with water, nitric acid (HNO₃) and nitrous acid (HNO₂) are formed as products. The balanced chemical equation for this reaction is: \(NO₂ (g) + H₂O (l) \rightarrow HNO₃ (aq) + HNO₂ (aq)\) Step 2: Write the equation for NO reacting with water.

Step 2: Formation of nitrous acid from NO

When nitric oxide (NO) reacts with water, nitrous acid (HNO₂) and hydroxylamine (NH₂OH) are formed as products. The balanced chemical equation for this reaction is: \(2NO (g) + 2H₂O (l) \rightarrow 2HNO₂ (aq) + NH₂OH (aq)\) Now we have both reactions showing the formation of acids from nitrogen oxides reacting with water.

Key Concepts

Nitrogen Oxides

Nitrogen oxides are a group of gases that play a crucial role in environmental chemistry. These gases include primarily nitrogen dioxide \((\mathrm{NO}_2)\) and nitric oxide \((\mathrm{NO})\). Nitrogen oxides are introduced into the atmosphere through both natural processes, like lightning, and human activities, such as burning fossil fuels. Once in the atmosphere, they contribute to a range of environmental issues.

• They are key precursors to acid rain.
• Nitrogen oxides also have effects on respiratory health.
• They participate in the formation of ozone at ground level.

Understanding the transformations of these compounds is essential for addressing their impact on the environment and public health.

Chemical Reactions

Chemical reactions are processes where substances are transformed into new products with different properties. In the context of nitrogen oxides, these reactions are critical for understanding how these compounds interact with other elements and compounds in the environment.

• For example, nitrogen dioxide \((\mathrm{NO}_2)\) reacts with water to form acids.
• The chemical equations involved are crucial for predicting the outcomes and impacts of these reactions.

These reactions are balanced, meaning the number of atoms for each element are conserved in the process. For nitrogen oxide reactions, this means careful consideration of reactants and products to ensure the chemical equations adhere to the Law of Conservation of Mass.

Nitric Acid Synthesis

Nitric acid \((\mathrm{HNO}_3)\) is a strong acid formed when nitrogen dioxide \((\mathrm{NO}_2)\) reacts with water. This reaction is an integral part of the process contributing to acid rain formation. The equation for this reaction is: \[\mathrm{NO}_2 (g) + \mathrm{H}_2\mathrm{O} (l) \rightarrow \mathrm{HNO}_3 (aq) + \mathrm{HNO}_2 (aq)\]This balanced chemical equation shows that both nitric acid and nitrous acid \((\mathrm{HNO}_2)\) are produced when \(\mathrm{NO}_2\) is dissolved in water.

• Nitric acid formation is a major pathway for nitrogen oxides to contribute to acid rain.
• The presence of nitric acid can lead to lowered pH levels in rainwater, adversely affecting ecosystems.

Nitrous Acid Formation

Nitrous acid \((\mathrm{HNO}_2)\) is another product formed in reactions of nitrogen oxides with water. In the case of nitric oxide \((\mathrm{NO})\), it reacts with water following this equation:\[2\mathrm{NO} (g) + 2\mathrm{H}_2\mathrm{O} (l) \rightarrow 2\mathrm{HNO}_2 (aq) + \mathrm{NH}_2\mathrm{OH} (aq)\]In addition to producing nitrous acid, hydroxylamine \((\mathrm{NH}_2\mathrm{OH})\) is also formed. These reactions highlight the transformative nature of chemical reactions involving nitrogen oxides.

• Nitrous acid is a weaker acid than nitric acid but still contributes to environmental acidity.
• This acid can further decompose and participate in various atmospheric chemical processes, influencing environmental conditions.

Understanding these reactions is important for comprehending how nitrogen oxides alter the chemistry of our atmosphere.