Problem 65 - Chemistry: The Central Science

Question

Write balanced chemical equations for each of the following reactions: (a) The nitric oxide molecule undergoes photodissociation in the upper atmosphere. (b) The nitric oxide molecule undergoes photoionization in the upper atmosphere. (c) Nitric oxide undergoes oxidation by ozone in the stratosphere. (d) Nitrogen dioxide dissolves in water to form nitric acid and nitric oxide.

Step-by-Step Solution

Answer

(a) The photodissociation of nitric oxide: \( NO \xrightarrow{h\nu} N + O \) (b) The photoionization of nitric oxide: \( NO \xrightarrow{h\nu} NO^{+} + e^{-} \) (c) The oxidation of nitric oxide by ozone: \( NO + O_3 \longrightarrow NO_{2} + O_{2} \) (d) The dissolution of nitrogen dioxide in water: \( 2 NO_{2} + H_{2}O \longrightarrow HNO_{3} + NO \)

Step 1: Determine the photodissociation reaction

In this reaction, nitric oxide (NO) absorbs ultraviolet radiation and breaks down into its constituent elements, nitrogen (N) and oxygen (O).

Step 2: Write the equation

The photodissociation of nitric oxide can be written as: \( NO \xrightarrow{h\nu} N + O \) (b) Photoionization of nitric oxide in the upper atmosphere

Step 3: Determine the photoionization reaction

During photoionization, nitric oxide (NO) absorbs ultraviolet radiation and becomes ionized, losing an electron. The process generates nitric oxide ions (NO⁺) and free electrons (e⁻).

Step 4: Write the equation

The photoionization of nitric oxide can be written as: \( NO \xrightarrow{h\nu} NO^{+} + e^{-} \) (c) Oxidation of nitric oxide by ozone in the stratosphere

Step 5: Determine the oxidation reaction

In this reaction, nitric oxide (NO) reacts with ozone (O₃) and becomes oxidized to form nitrogen dioxide (NO₂) and diatomic oxygen (O₂).

Step 6: Write the equation

The oxidation of nitric oxide by ozone can be written as: \( NO + O_3 \longrightarrow NO_{2} + O_{2} \) (d) Dissolution of nitrogen dioxide in water to form nitric acid and nitric oxide

Step 7: Determine the dissolution reaction

In this reaction, nitrogen dioxide (NO₂) reacts with water (H₂O) to form nitric acid (HNO₃) and nitric oxide (NO).

Step 8: Write the equation

The dissolution of nitrogen dioxide in water can be written as: \( 2 NO_{2} + H_{2}O \longrightarrow HNO_{3} + NO \)