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This is a document of general chemistry.
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4.1 Colligative Properties Overview Nature of Solutions: Solutions have different properties than their constituent pure solute and solvent. Dependent Properties: Some properties of solutions like acidity, basicity, and density depend on the specific identity of the solute. Colligative Properties: These are specific properties that depend primarily on the concentration of solute particles rather than the nature or identity of the solute itself. Colligative Properties Discussed: Vapor Pressure Lowering: Definition: When a non-volatile solute is dissolved in a solvent, it results in the lowering of the vapor pressure of the solvent. This occurs because the solute molecules occupy space at the surface of the solution, thereby reducing the number of solvent molecules that can escape into the vapor phase. Units: The change in vapor pressure (ΔP) is measured in atmospheres (atm), millimeters of mercury (mmHg), or pascals (Pa). Boiling Point Elevation: Definition: The boiling point of a solution is higher than that of the pure solvent. This elevation in boiling point occurs because the presence of solute particles lowers the solvent's vapor pressure, requiring a higher temperature to reach the boiling point where the vapor pressure equals atmospheric pressure. Units: The change in boiling point (ΔT_b) is typically measured in degrees Celsius (°C) or Kelvin (K). Freezing Point Depression: Definition: The freezing point of a solution is lower than that of the pure solvent. This depression in freezing point can be explained by the disruption of the solvent’s crystal lattice formation by solute particles, requiring a lower temperature to solidify.
Units: The change in freezing point (ΔT_f) is typically measured in degrees Celsius (°C) or Kelvin (K). Osmotic Pressure: Definition: Osmotic pressure is the pressure that needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. This property reflects the tendency of solvent molecules to move from a region of lower solute concentration to one of higher solute concentration to equalize the solute concentrations on both sides of the membrane. Units: Osmotic pressure is measured in atmospheres (atm), bars, or pascals (Pa). 4.2 Concentration Units Molarity (M): Defined as moles of solute per liter of solution. Noted for being temperature dependent due to the volume changes with temperature variations. Mass Percent (%): Concentration expressed as the mass of the solute relative to the total mass of the solution, multiplied by 100. Mole Fraction (X): Defined as the moles of a component divided by the total moles in the solution. This measure is temperature-independent. Molality (m): Moles of solute per kilogram of solvent. It is also independent of temperature and uses the lowercase 'm' to differentiate from molarity. 4.3 Vapor Pressure Review Liquid-Vapor Equilibrium: In a closed system, a liquid and its vapor reach an equilibrium where vaporization and condensation rates are equal. Vapor Pressure: The pressure exerted by the gas phase molecules of a liquid in a closed system. Vapor Pressure Lowering (ΔP) Process: Equilibrium Shift: Adding a nonvolatile solute shifts the liquid-vapor equilibrium.
1.1 Acid and Base Definitions Originators: Defined by Johannes Brønsted and Thomas Lowry in 1923. Core Concept: Their theory focuses on the interactions between acids and bases through proton exchange. Definitions: Brønsted-Lowry Acid: A compound capable of donating a proton to another compound. Brønsted-Lowry Base: A compound capable of accepting a proton from another compound. Types of Acids and Bases: Acids: Molecules: Both organic (e.g., acetic acid) and inorganic (e.g., sulfuric acid). Cations containing Hydrogen: Such as hydronium ion (H₃O⁺). Anions containing Hydrogen: For example, hydrogen sulfate (HSO₄⁻). Bases: Ionic Compounds: Commonly those containing hydroxide (OH⁻). Molecules: Primarily amines (e.g., ammonia, NH₃). Anions: Both with and without hydrogen. Cations: There are few examples, but they exist. Conjugate Acid/Base Theory: Conjugate Base: Formed when an acid loses a proton. Conjugate Acid: Formed when a base gains a proton.