Nitrogen

### 1. Nitrogen Basics

Front:

Why is N₂ gas so unreactive?

Back:

Due to the high bond energy of the N≡N triple bond (requires significant energy to break).

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### 2. Ammonia Structure

Front:

What is the molecular shape of NH₃ and why?

Back:

Triangular pyramidal

- Nitrogen has 1 lone pair + 3 bonded pairs

- Lone pair repulsion distorts shape from tetrahedral

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### 3. Acid Rain Formation

Front:

What are the two main acids in acid rain, and their sources?

Back:

1. H₂SO₄ (from SO₂ combustion)

2. HNO₃ (from NOₓ via):

\[ 2NO₂ + H₂O → HNO₃ + HNO₂\]

\[4NO₂ + O₂ + 2H₂O → 4HNO₃\]

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### 4. Photochemical Smog

Front:

What 3 conditions are required for photochemical smog?

Back:

1. NOₓ (from vehicles)

2. VOCs (unburned fuels)

3. Sunlight (UV drives reactions)

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### 5. Catalytic Converters

Front:

Balance the catalytic converter reaction and state oxidation changes:

\[ \text{NO} + \text{CO} → \_\_\_ + \_\_\_ \]

Back:

\[ 2NO + 2CO → N₂ + 2CO₂ \]

- NO reduced (+2 → 0)

- CO oxidized (+2 → +4)

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### 6. Secondary Pollutants

Front:

Why is PAN called a "secondary pollutant"?

Back:

It forms indirectly from reactions between:

- NOₓ + VOCs + sunlight

(Not directly emitted like NOₓ from tailpipes)

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### 7. Ammonium Salt Test

Front:

How to test for NH₄⁺ ions in the lab?

Back:

1. Heat with NaOH

2. Ammonia gas turns damp red litmus blue

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### 8. Smog vs Acid Rain

Front:

Compare the primary pollutants in smog vs acid rain.

Back:

| Smog | Acid Rain |

|----------------|------------------|

| NOₓ + VOCs | SO₂ + NOₓ |

| Forms O₃/PAN | Forms H₂SO₄/HNO₃ |