Matter, Solutions, and Gases: Chemistry Fundamentals

Matter Composition

- Matter: Formed of two or more pure substances.

Heterogeneous Mixtures

1. Heterogeneous: Non-uniform composition.

Homogeneous Mixtures

2. Homogeneous: Uniform composition, small particles.

Solutions

- Solution: Homogeneous mixture, small particles, liquid solutions are transparent.
- Solute: Smaller amount.
- Solvent: Larger amount, often water (aqueous).

Colloids

- Colloid: Mixtures with larger particles.

Electrolytes

- Electrolytes: Allow water to conduct electricity due to ions in the solution. Strong electronegativity.
Examples:
- Acids: HCl, HNO₃, H₂SO₄
- Salts: K⁺, Na⁺, NH₄⁺, NO₃^-
Example of Dissociation:
NaCl → Na⁺ + Cl^-

Non-Electrolytes

- Molecules, polar for H₂O, sugars; polar solute dissolves in a polar solvent.

Hydrogen Bonding

- Molecules containing OH or NH can form hydrogen bonds. If there are many carbons in a water-soluble molecule. Example: Ethanol (CH₃CH₂OH) can hydrogen bond with water.

Non-Polar Solvents

- Non-polar dissolves in non-polar: Octane (C₈H₁₈) dissolves in CCl₄ because both are non-polar liquids exhibiting only London dispersion forces.

Dissolving Energy Change

- Exothermic: Heat released when some solutes dissolve in a solvent. Example: HCl, NaOH
- Endothermic: Heat absorbed when solutes dissolve in a solvent. Example: NH₄Cl, sucrose

Solubility

- Solubility: Amount of solute that dissolves in a given amount of solvent.
- Saturated: Contains the maximum amount of solute that can dissolve.
- Unsaturated: Contains less than the maximum amount.
- Supersaturated: Contains more than the maximum amount.

Temperature Effects

- For gases, solubility decreases with increasing temperature.

Pressure Effects

- The higher the pressure, the more soluble a gas is in a solution.

Gas Properties

- Gases consist of particles (atoms or molecules) moving randomly and rapidly.
- The size of gas particles is small compared to the distances between them.
- Gas particles exert no attractive forces (ideal gas assumption).
- The kinetic energy of gas particles increases with increasing temperature.
- When gas particles collide, they rebound and travel in new directions.

Gas Pressure Units

- 1 atm = 760 mmHg = 760 torr = 14.7 psi = 101,325 Pa

Gas Laws

- Boyle's Law: Temperature constant, P₁V₁ = P₂V₂ (inverse relationship).
- Charles's Law: Pressure constant, V₁/T₁ = V₂/T₂ (direct relationship).
- Gay-Lussac's Law: Volume constant, P₁/T₁ = P₂/T₂ (direct relationship).
- STP Conditions: 1 atm, 273 K, 22.4 L/mol.
- Dalton's Law of Partial Pressures: P_total = P₁ + P₂ + ...
- Ideal Gas Law: PV = nRT
- Combined Gas Law: T₂ = (P₂V₂T₁) / (P₁V₁)