Dissolving and Solutions Overview

  • Dissolving Process

    • Definition: Dissolving occurs when substances break apart in a solvent.
    • Example: Dissolving sodium chloride (NaCl) in water.

  • Key Concepts:

    • Water as a Universal Solvent:
    • Water (H₂O) is polar with partial charges.
    • Uses partial charges to interact with ions and break down crystal lattice.
    • Terms:
    • Solute: Substance that is dissolved (e.g., NaCl).
    • Solvent: Substance that does the dissolving (e.g., water).
    • Dissociation:
    • Process where ionic compounds split into ions in a solution.

  • Electrolytes:

    • Solutions that can conduct electricity due to dissociated ions.
    • Aqueous solutions of ionic compounds (e.g., NaCl) are typical electrolytes.

  • Different Types of Substances:

    • Ionic Compounds: Dissolve well in water and dissociate into ions.
    • Covalent Compounds:
    • Polar Covalent: May dissolve slightly in water (e.g., acetic acid).
    • Nonpolar Covalent: Generally do not dissolve in water (e.g., oil).
    • Like Dissolves Like: Substances with similar polarities dissolve each other.

  • Examples:

    • Acids (e.g., HCl, NaOH) typically dissociate in water, acting as electrolytes.
    • Nonpolar substances (e.g., methane, CH₄) do not significantly dissolve in water.

  • Visual Concept:

    • When Na₂S is dissolved in water, the water molecules surround and separate the Na⁺ and S²⁻ ions due to attraction between partial charges of water and full charges of ions.

  • Questions:

    1. Difference between solute and solvent:
    • Solute: Being dissolved.
    • Solvent: Doing the dissolving.
    1. Why are aqueous ionic compounds electrolytes?
    • They dissociate into mobile ions in solution, allowing electricity to conduct.
    1. Example of solute and solvent in acetic acid solution:
    • Acetic acid = solute, water = solvent.