General Chemistry 101 Notes

Water as a Solvent

• Water is a polar solvent.
• Dissolves most ionic and some organic compounds.
• Guideline: "like dissolves like".

Aqueous Solutions

• Solution: Homogeneous mixture (solute + solvent).
• Solute: Smaller amount, dissolved.
• Solvent: Larger amount, the medium.

Types of Solutions

• Gaseous: Example - Air.
• Liquid: Example - Salt in water.
• Solid: Example - Alloys.

Electrolytes

• Electrolyte: Conducts electricity when dissolved.
  • Strong Electrolytes: Completely ionize in water (e.g., HCl, NaOH).
  • Weak Electrolytes: Partially ionize (e.g., CH3COOH).
• Non-electrolytes: Do not conduct electricity (e.g., glucose).

Precipitation Reactions

• Common reaction in aqueous solutions.
• Forms an insoluble product (precipitate).
• Example: { ext{Pb(NO}3 ext{)}2(aq) + 2 ext{KI}(aq)
  ightarrow ext{PbI}2(s) + 2 ext{KNO}3(aq)}.

Solubility Rules

• Soluble: Alkali metal ions, ammonium, nitrates, chlorates.
• Insoluble: Carbonates, phosphates, sulfides (except those of alkali metals).
  • Important exceptions: CaSO4, BaSO4, and AgCl.

Acids and Bases

• Arrhenius definition:
  • Acids produce H+ in water.
  • Bases produce OH- in water.
• Brønsted definition:
  • Acid: Proton donor.
  • Base: Proton acceptor.
• Strong Acids: Completely ionize (e.g., HCl, H2SO4).
• Weak Acids: Partially ionize (e.g., HNO2, CH3COOH).

Net Ionic Equations

• Shows only ions that participate in reactions.
• E.g., For acid-base reactions: { ext{H}^+ (aq) + ext{OH}^- (aq)
  ightarrow ext{H}_2 ext{O}(l)}.

Molarity and Dilution

• Molarity (M): Moles of solute per liter of solution.
• Dilution Formula: ${M<em>1V</em>1 = M<em>2V</em>2}$.

Titration

• Standard solution added to unknown until reaction completion.
• Indicators: Change color at equivalence point.