chemistry review

UNIT B CHEMISTRY STUDY GUIDE

Acids & Bases | Chemistry and the Environment | Organic Chemistry

PART 1: ACIDS & BASES

What are Acids and Bases?

Acid-Base Theories

• Arrhenius Definition:

  • Acid: Increases H⁺ in water.

  • Base: Increases OH⁻ in water.

• Brønsted-Lowry Definition:

  • Acid: Proton (H⁺) donor.

  • Base: Proton (H⁺) acceptor.

Strong vs. Weak Acids and Bases

• Strong: Fully ionize in water (e.g., HCl, NaOH).

• Weak: Partially ionize (e.g., CH₃COOH, NH₃).

pH Scale & Calculations

• Scale from 0 to 14:

  • 0–6 = acidic, 7 = neutral, 8–14 = basic

• pH = -log[H⁺]

• A change in 1 pH unit = 10× difference in [H⁺]

Neutralization Reactions

• Acid + Base → Salt + Water

  • Example: HCl + NaOH → NaCl + H₂O

Titration

Used to find the concentration of an unknown acid or base using a known one.

Steps:

1. Add acid to base (or vice versa) using a burette.

2. Use an indicator (e.g., phenolphthalein).

3. Calculate unknown concentration using:

   • n = C × V (mol = concentration × volume)

   • C = n ÷ V

PART 2: CHEMISTRY & THE ENVIRONMENT

Combustion Reactions

• Complete Combustion: Fuel + O₂ → CO₂ + H₂O

  • Clean burn, efficient energy

• Incomplete Combustion: Fuel + limited O₂ → CO + C (soot) + H₂O

  • Produces carbon monoxide, a toxic gas

Acid Rain & Air Pollutants

• Sulfur Dioxide (SO₂) from coal burning:

  • SO₂ + H₂O → H₂SO₃ (sulfurous acid)

  • SO₃ + H₂O → H₂SO₄ (sulfuric acid)

• Nitrogen Oxides (NO, NO₂) from engines:

  • NO₂ + H₂O → HNO₃ (nitric acid)

These acids fall as acid rain, harming:

• Aquatic life (lowers lake pH)

• Plants (damages leaves, leaches nutrients)

• Infrastructure (corrodes buildings/statues)

• Human health (respiratory issues)

Buffering the Environment

• Limestone (CaCO₃): Natural base that neutralizes acids in soil and water.

Controlling Emissions

• Scrubbers: Remove SO₂ from smokestacks using limestone slurries.

• Catalytic Converters: Reduce NO and CO in car exhaust by converting them to N₂ and CO₂.

Smog & Ozone Formation

• Sunlight + NO₂ → NO + O

• O + O₂ → O₃ (ozone, part of photochemical smog)

Effects: Eye irritation, breathing problems, damage to crops.

Concentration Units

• ppm (parts per million): 1 mg/L

• ppb (parts per billion): 1 μg/L

PART 3: ORGANIC CHEMISTRY

What is Organic Chemistry?

The study of carbon-based compounds, especially hydrocarbons and their derivatives.

Hydrocarbons

Compounds made of only carbon and hydrogen.

Functional Groups

Groups of atoms that give molecules specific chemical properties and uses.

Naming Organic Compounds

1. Find the longest carbon chain with the functional group.

2. Number the chain from the end closest to the functional group.

3. Name branches (methyl, ethyl, etc.).

4. Use correct suffix based on the functional group.

5. For esters: name alcohol part first, acid part second.

Example:

• Butanoic acid: 4 carbon acid

• 2-butanol: 4 carbon chain with OH on 2nd carbon

• Ethyl ethanoate: Ester made from ethanol + ethanoic acid

Making Esters (Esterification)

Alcohol + Carboxylic Acid → Ester + Water

Example:
Ethanol + Propanoic Acid → Ethyl Propanoate + H₂O

Structural Diagrams

• Each carbon makes 4 bonds

• Hydrogen makes 1 bond

• Oxygen makes 2 bonds

• Nitrogen makes 3 bonds

Quick Memory Tips

• Acids donate H⁺, bases accept H⁺

• Acid rain comes from burning fossil fuels

• Esters = fruity smell (think “Ester = Easter = candy”)

• Alcohol = OH = “Oh hi!” (disinfectants, drinking)

• Carboxylic acid = sour (think vinegar or lemon)