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Ch.18 - Chemistry of the Environment
Chapter 18, Problem 27

Nitrogen oxides like NO2 and 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.

Verified step by step guidance
1
Identify the nitrogen oxides involved in the problem: NO2 and NO.
For NO2, write the balanced chemical equation for its reaction with water. NO2 reacts with water to form nitric acid (HNO3) and nitrous acid (HNO2). The equation is: 2 NO2 + H2O -> HNO3 + HNO2.
For NO, consider that it first reacts with oxygen to form NO2. The equation is: 2 NO + O2 -> 2 NO2.
Once NO is converted to NO2, use the equation from step 2 to show how NO2 reacts with water to form acids.
Summarize the process: NO is first oxidized to NO2, which then reacts with water to form nitric acid and nitrous acid, contributing to acid rain.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid-Base Reactions

Acid-base reactions involve the transfer of protons (H+) between substances. In the context of nitrogen oxides, these reactions occur when NO2 and NO interact with water, leading to the formation of acids. Understanding the Brønsted-Lowry theory, which defines acids as proton donors and bases as proton acceptors, is essential for predicting the products of these reactions.
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Formation of Nitric Acid

When nitrogen dioxide (NO2) reacts with water, it forms nitric acid (HNO3). The reaction can be represented as: 3 NO2 + H2O → 2 HNO3 + HNO. This process is significant in the context of acid rain, as nitric acid contributes to the acidity of precipitation, impacting ecosystems and human structures.
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Formation of Nitrous Acid

Nitric oxide (NO) can react with water to form nitrous acid (HNO2). The reaction is represented as: 2 NO + H2O → HNO2 + HNO. This reaction is also relevant to acid rain, as nitrous acid can further dissociate in water, contributing to the overall acidity of rainwater and its environmental effects.
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