Acid-Base Chemistry and Equilibrium - Week 11

Acid-Base Chemistry and Equilibrium - Week 11

• Definitions
  • Arrhenius: Acids produce H⁺ in water; bases produce OH⁻.
  • Brønsted-Lowry: Acids donate protons (H⁺), bases accept protons.
• Characteristics
  • Strong acids/bases completely dissociate in water (e.g., HCl → H⁺ + Cl⁻).
  • Weak acids/bases partially dissociate; their equilibrium is described by dissociation constants (Ka for acids, Kb for bases).
• Autoionization of Water
  • H₂O + H₂O ⇌ H₃O⁺ + OH⁻
  • Kw = [H₃O⁺][OH⁻] = 1.0 × 10⁻¹⁴ (at 25°C)

Calculating pH and Related Concentrations

• pH and pOH
  • pH = -log[H₃O⁺]
  • pOH = -log[OH⁻]
  • pH + pOH = 14 (at 25°C)
• Concentration Relationships
  • If [H₃O⁺] is known, calculate [OH⁻] using [OH⁻] = Kw / [H₃O⁺]. Vice versa.
  • Example: If [H₃O⁺] = 4.0 × 10⁻⁸ M, then [OH⁻] = 2.5 × 10⁻⁷ M.

Polyprotic Acids and Buffers

• Polyprotic Acids
  • Have multiple ionizable protons (e.g., H₂SO₄, H₃PO₄).
  • Ionization occurs in steps, with Ka₁ > Ka₂ > Ka₃.
• Buffers
  • Consist of a weak acid and its conjugate base, or a weak base and its conjugate acid (e.g., CH₃COOH/CH₃COO⁻).
  • Buffer capacity is greater with equal or similar concentrations of both components.

Neutralization and Titrations

• Neutralization Reaction
  • Acid + Base → Salt + Water (e.g., HCl + NaOH → NaCl + H₂O).
• Titrations
  • Used to determine unknown concentrations.
  • Key Formula: M₁V₁ = M₂V₂ (for monoprotic acids & bases).
  • Example: If 12.0 mL of HCl reacts with 25.0 mL of 0.20 M KOH, the concentration of HCl is 0.42 M.

Biological Importance of Acids, Bases, and Buffers

• Buffers in the Body
  • Bicarbonate buffer regulates blood pH by converting HCO₃⁻ and H₂CO₃.
  • Phosphate buffer maintains cellular pH.
  • Protein buffers act by binding H⁺ or OH⁻.
  • Stable pH is crucial for enzyme function and biochemical reactions.

Organic Chemistry - Week 12

• Definition: Study of carbon-containing compounds and their properties, reactions, and preparation.
• Key Elements: Carbon (C) and Hydrogen (H) often with Nitrogen (N), Oxygen (O), Halogens, Sulfur (S), or Phosphorus (P).
• Carbon Traits: Forms strong covalent bonds, chains & rings (catenation), and single, double, and triple bonds.

Hydrocarbons

• Definition: Organic compounds composed solely of carbon and hydrogen.
• Types & Formulas
  • Alkanes (CnH₂n₊₂): single C-C bonds (saturated)
  • Alkenes (CnH₂n): one or more C=C double bonds (unsaturated)
  • Alkynes (CnH₂n₋₂): one or more C≡C triple bonds (unsaturated)
• Cyclic Hydrocarbons
  • Examples include cyclohexane (C₆H₁₂) and benzene (C₆H₆). Benzene displays resonance.

Writing Structures for Organic Molecules

• Molecular Formula: Shows the number of each type of atom.
• Lewis Structure: Displays all atoms and bonds explicitly.
• Condensed Formula: Groups atoms.
• Skeletal (Line) Structures: Carbon atoms are implied at line ends/intersections, hydrogens are not shown.
• Space-Filling Models: Illustrate 3D molecular shapes.

Organic Functional Groups

• Definition: Specific groupings of atoms that determine chemical behavior.
• Common Functional Groups: Alcohol (R-OH), Carboxylic Acid (R-COOH), Aldehyde (R-CHO), Ketone (R₂CO), Ether (R-O-R'), Ester (R-COO-R'), Amine (R-NH₂), Amide (R-CONH₂), Phenol (Ar-OH).

Polymers in Organic Chemistry

• Definition: Large molecules composed of repeating monomer units.
• Examples: Polyethylene (LDPE & HDPE), Polyvinyl Chloride (PVC), Polystyrene (PS), Nylon, and Teflon.

Biomolecules- Week 13

• Four Major Classes: Carbohydrates, Lipids, Proteins, Nucleic Acids.

Carbohydrates

• Structure: Monosaccharides (simple sugars), Disaccharides (two monosaccharides joined by glycosidic bonds), and Polysaccharides (long chains).
• Formation & Breakdown: Dehydration synthesis (water forms) and hydrolysis(water breaks down).

Lipids

• Types: Fatty acids, triglycerides, phospholipids, steroids.
• Key Concepts: Omega-3 and Omega-6, cis vs. trans fats.

Proteins

• Structure: Made of amino acids linked by peptide bonds. Four levels: Primary, secondary, tertiary, quaternary.
• Functions: Enzymes, transport, immunity.

Nucleic Acids

• Types: DNA (double helix), RNA (single helix).
• Processes: e.g., gene editing (CRISPR-Cas9), protein synthesis.

Nuclear Chemistry - Week 14

• Atomic Structure Basics
  • Key Terms: Isotopes (atoms of same element with different neutrons), nucleons (protons + neutrons), nuclide (particular type of nucleus with specific protons & neutrons). Mass number (protons + neutrons), Atomic number (number of protons).
• Nuclear Chemistry Fundamentals
  • Definition: The study of changes in the nucleus of an atom. Nuclear reactions involve changes to the nucleus; chemical reactions to electrons.
  • Types of Radioactivity: Alpha (α) decay, Beta (β) decay, Gamma (γ) decay, Positron Emission, Electron Capture
• Half-life: Time for half of a radioactive sample to decay.

Safety and Environmental Impact of Nuclear Chemistry

• Nuclear Power Pros: Low operating costs, high-energy output, and reduced greenhouse gas emissions
• Nuclear Power Cons: Challenges in waste disposal, risks of accidents and terrorism, and limited uranium resources.

Test your understanding of acid-base chemistry and equilibrium concepts covered in Week 11. This quiz includes definitions, characteristics of acids and bases, pH calculations, and information on polyprotic acids and buffers. Challenge yourself and reinforce your knowledge of these vital chemistry principles.