2020-CHE-Chemistry-Notes-Module-5-6

Static and Dynamic Equilibrium
- Inquiry: What happens when chemical reactions do not go through to completion?
  - Investigate reversible nature of reactions, e.g., cobalt(II) chloride.
  - Model static vs dynamic equilibrium, analyze open vs closed systems.
  - Examine non-equilibrium systems: combustion reactions, photosynthesis.
  - Relationship between collision theory and reaction rate in equilibrium reactions.
Factors Affecting Equilibrium
- Inquiry: What factors affect equilibrium and how?
  - Effects of temperature, concentration, volume, and pressure at equilibrium.
  - Use of Le Chatelier’s principle to predict equilibrium shifts.
    - Example investigations: Heating cobalt(II) chloride hydrate.
    - Reaction analysis: nitrogen dioxide with dinitrogen tetroxide; iron(III) thiocyanate.
Calculating Equilibrium Constant (Keq)
- Inquiry: What does the equilibrium constant represent?
  - Deduction of equilibrium expression for homogeneous reactions.
  - Calculations for Keq and predicting reaction direction.
  - Investigation of temperature effects on Keq values.

Solubility and Chemical Equilibrium
- Inquiry: How does solubility relate to chemical equilibrium?
  - Analyze dissolution of ionic compounds.
  - Historical use: Aboriginal and Torres Strait Islander Peoples removing toxins.
  - Investigate solubility rules, e.g., potassium chloride and silver nitrate.
  - Derive equilibrium expressions from Ksp and predict precipitate formation.

Enthalpy Change
- Enthalpy (H): Measure of heat content.
  - Change in enthalpy (∆H) provides insights into energy absorption/release during reactions.
  - Exothermic: ∆H < 0; Endothermic: ∆H > 0.
Energy Profile Diagrams
Hess’s Law of Heat Summation: Total enthalpy change of a reaction is constant regardless of the steps taken.

Bond Energies
- Definition: Energy required to break one mole of a bond in gas phase.
- Calculating reaction enthalpy changes based on bond energies.
Entropy (S)
- Measure of energy distribution among particles; associated with disorder.
- Factors affecting entropy include:
  - Particle number, molecular complexity, volume, and temperature.
- Second Law of Thermodynamics: Entropy of the universe increases.

Equilibrium dynamics: Static vs dynamic equilibrium.
Types of Systems: Open, closed, isolated.
Rates of Reaction: Affected by concentration, surface area, temperature, catalyst presence, and reactivity.

Essential for understanding reaction rates and mechanisms.
Effective collisions yield products; factors influencing effective collisions include:
- Temperature: Higher energy increases frequency.
- Concentration: More particles increase chances of collisions.
- Surface area: More exposure increases interaction rates.

Application of Principle: Shifts in equilibrium due to concentration, volume, pressure, and temperature changes.
- Predict equilibrium response: Addition/removal of reaction components; change in conditions.

Apply Le Chatelier’s principle to observe qualitative shifts during perturbations in equilibrium.
Investigate specific reactions and predict outcomes based on equilibrium constants and concentrations.

Define and calculate the equilibrium expression for various reactions types.
Interpret Keq Values: Indication of reaction favoring products or reactants via K values.

Ksp Calculations and Predictions
- Equilibrium dynamics of ionic solutions and potential precipitate formation.
- Balance the equations involving ionic dissociation and solubility product constants (Ksp).

Strong vs Weak Acids: Differences in ionization in aqueous solutions.
- Strength correlates with complete versus partial ionization in solvent.
pKa Relationships and Ionization Degree: Calculating concentrations and comparing various acid strengths.

Buffer Systems: How they mitigate pH change and the role of weak acids and conjugate bases.
Titration: In-depth process analysis to determine concentrations of unknown solutions.
Evaluate acid/base behaviors in practical environments and laboratory settings.