Acids and Bases

Properties and Definitions of Acids

Acids are substances that donate hydrogen ions (H+) in chemical reactions. They have distinct properties and play a central role in many chemical processes.

• Properties of Acids:

  • Taste sour

  • Dissolve many metals

  • Turn blue litmus paper red

  • Produce H+ (or H3O+) in water

• Common Acids and Uses:

  • Hydrochloric acid (HCl): Stomach acid, metal cleaning

  • Sulfuric acid (H2SO4): Car batteries

  • Nitric acid (HNO3): Fertilizers, explosives

  • Acetic acid (HC2H3O2): Vinegar

  • Citric acid (C6H8O7): Citrus fruits

Properties and Definitions of Bases

Bases are substances that accept hydrogen ions or produce hydroxide ions (OH-) in water. They are essential in neutralization reactions and industrial processes.

• Properties of Bases:

  • Taste bitter

  • Feel slippery

  • Turn red litmus paper blue

  • Produce OH- in water

• Common Bases and Uses:

  • Sodium hydroxide (NaOH): Drain cleaner

  • Potassium hydroxide (KOH): Soap making

  • Sodium bicarbonate (NaHCO3): Baking soda, antacids

• Strong Bases: LiOH, NaOH, KOH, Ca(OH)2, Sr(OH)2, Ba(OH)2

• Weak Bases: Ammonia (NH3), pyridine, methylamine, ethylamine

Arrhenius and Brønsted–Lowry Definitions

• Arrhenius Acid: Produces H+ ions in water Example:

• Arrhenius Base: Produces OH- ions in water Example:

• Brønsted–Lowry Acid: Donates a proton (H+)

• Brønsted–Lowry Base: Accepts a proton (H+)

Conjugate Acid-Base Pairs

Conjugate acid-base pairs are two substances that differ by one H+ ion.

• When an acid loses H+, it becomes its conjugate base.

• When a base gains H+, it becomes its conjugate acid.

• Example: NH3 = base, NH4+ = conjugate acid

Amphoteric Substances

Amphoteric substances can act as either an acid or a base. Water is a classic example.

• Self-ionization of water:

Neutralization Reactions

Neutralization occurs when an acid reacts with a base to produce water and a salt.

• General Equation: Acid + Base → Water + Salt

• Example:

• Net Ionic Equation:

Other Acid Reactions

• Acid + Metal: Produces hydrogen gas and a salt Example:

• Acid + Metal Oxide: Produces water and a salt Example:

Acid-Base Titration

Titration is a laboratory method used to determine the unknown concentration of an acid or base by reacting it with a solution of known concentration.

• Equivalence Point: Moles of acid = moles of base; neither reactant is left over

• Indicator: A substance (e.g., phenolphthalein) that changes color at the equivalence point

• Formula for 1:1 reactions:

Strong vs. Weak Acids and Bases

• Strong Acids: Completely ionize in water (100% as ions)

  • Examples: HCl, HBr, HI, HNO3, HClO4, H2SO4 (first H+ only)

  • Equation:

• Weak Acids: Partially ionize in water

  • Examples: HF, acetic acid, formic acid, carbonic acid, phosphoric acid, sulfurous acid

  • Equation:

• Strong Bases: LiOH, NaOH, KOH, Ca(OH)2, Sr(OH)2, Ba(OH)2

• Weak Bases: NH3, pyridine, methylamine, ethylamine

Ion Product Constant for Water (Kw)

The ion product constant for water (Kw) describes the relationship between the concentrations of H+ and OH- in water.

• At 25°C:

• If you know one concentration, you can calculate the other.

pH and pOH

The pH scale measures how acidic or basic a solution is. pOH is a related measure for hydroxide ion concentration.

• pH:

• pOH:

• Relationship:

• Find Concentration: ,

pH Scale and Solution Classification

• pH < 7: Acidic

• pH = 7: Neutral

• pH > 7: Basic (alkaline)

• A difference of 1 pH unit = 10× change in acidity

Buffers

A buffer is a solution that resists changes in pH when small amounts of acid or base are added. Buffers are crucial in biological systems.

• Contains a weak acid and its conjugate base, or a weak base and its conjugate acid

• Example: Blood (normal pH 7.36–7.40), acetic acid/acetate buffer

Organic Chemistry

Introduction to Organic Chemistry

Organic chemistry is the study of carbon-containing compounds, their structures, properties, and reactions. Most organic compounds contain carbon, hydrogen, and often oxygen, nitrogen, sulfur, or halogens.

• Organic Compounds: Originally believed to come only from living things; decompose easily; difficult to synthesize in the lab

• Inorganic Compounds: From nonliving sources; harder to decompose; often easier to synthesize

• Vitalism: The outdated belief that only living organisms could produce organic compounds

Hydrocarbons

Hydrocarbons are organic compounds made of only carbon and hydrogen. They are the foundation of organic chemistry and are classified by the types of bonds between carbon atoms.

• Alkanes: Only single bonds (saturated hydrocarbons)

  • General formula:

  • Names end in -ane

  • Example: Propane ()

• Alkenes: At least one double bond (unsaturated hydrocarbons)

  • General formula:

  • Names end in -ene

  • Example: Ethene ()

• Aromatic Hydrocarbons: Contain one or more benzene rings (e.g., benzene )

Naming Hydrocarbons

Hydrocarbons are named using prefixes for the number of carbons and suffixes for the type of bond.

• -ane: single bonds (alkanes)

• -ene: double bonds (alkenes)

• Number the chain from the end closest to the double bond

Structural Isomers

Structural isomers have the same molecular formula but different structural arrangements of their atoms, leading to different properties.

• Example: Butane and 2-methylpropane ()

Physical Properties of Hydrocarbons

• As the number of carbon atoms increases, boiling point increases

• Straight-chain hydrocarbons have higher boiling points than branched ones with the same formula

• Larger molecules have stronger intermolecular forces

• Boiling Point Order Example:

Hydrocarbon Reactions

• Substitution Reaction: One atom is replaced by another (common in alkanes)

• Addition Reaction: Atoms are added across a double bond (common in alkenes)

  • Example: (Addition)

Aromatic Hydrocarbons (Benzene)

• Benzene ring: six-carbon ring with alternating single and double bonds

• Formula:

• Substituent positions:

  • Ortho (o-): 1,2-

  • Meta (m-): 1,3-

  • Para (p-): 1,4-

Functional Groups

Functional groups are specific groups of atoms that determine the properties and reactions of organic compounds.

Alcohols, Ethers, and Esters

• Alcohol: Functional group -OH, suffix -ol

• Ether: Functional group R-O-R, oxygen bonded to two carbons

• Ester: Functional group -COO-, formed from a carboxylic acid and an alcohol, suffix -oate

Common Alkyl Groups

Key Equations and Relationships

• Titration (1:1):

• pH:

• pOH:

• Relationship:

• Water Ion Product:

• Alkanes:

• Alkenes:

Additional info: Some formulas and tables were expanded for clarity and completeness. The notes integrate content from both acid-base and organic chemistry chapters, providing a comprehensive overview suitable for introductory college chemistry.