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In-Depth Notes on Solutions for 10th Grade Chemistry

SOLUTIONS

  • Definition: A homogeneous mixture.

  • Components:

    • Solute: The substance that is dissolved.

    • Solvent: The medium that dissolves the solute.

TYPES OF SOLUTIONS

  • Gas in Gas: Air (composition: nitrogen, oxygen, argon)

  • Liquid in Gas: Humid air (water vapor in air)

  • Solid in Gas: Smog

  • Gas in Liquid: Carbonated drinks

  • Liquid in Liquid: Vinegar (acetic acid in water)

  • Solid in Liquid: Salt water

  • Gas in Solid: Styrofoam

  • Liquid in Solid: Dental amalgam (mercury in silver)

  • Solid in Solid: Sterling silver (copper in silver)

HOW DOES A SOLUTION FORM?

  • When sodium chloride (NaCl) is placed in water:

    • Water molecules surround and interact with the NaCl crystal.

    • Water separates the positive ions (cations) and negative ions (anions).

    • Cations are surrounded by negatively charged oxygen in water.

    • Anions are surrounded by positively charged hydrogen in water.

SOLUBILITY

  • Definition: The ability of a solute to dissolve in a solvent to form a solution.

DISSOLVING/DISSOCIATION EQUATIONS

  • Dissociation: The process when an ionic compound breaks into ions in a solvent.

  • Dissociation equations must represent the process accurately.

FACTORS AFFECTING SOLUBILITY

  • Phases of Matter:

    • Solids: Strong intermolecular forces (IMFs) make solubility harder.

    • Liquids: Weaker IMFs allow mixing with solvents.

    • Gases: Weakest IMFs lead to higher solubility.

  • Quantity of Solvent:

    • Increased solvent volume can boost dissolution but has limits.

  • Polarity:

    • "Like dissolves like": Polar solutes dissolve in polar solvents; nonpolar solutes in nonpolar solvents.

    • Example:

    • Polar solute (e.g., C12H22O11) soluble in polar solvent; Nonpolar solute (e.g., C10H8) insoluble in polar solvents.

  • Pressure:

    • Increased pressure enhances gas solubility in liquids; negligible effect on solids and liquids.

  • Temperature:

    • Generally, higher temperatures increase solid and liquid solubility; may decrease gas solubility.

SOLUBILITY RULES

  • Solubility Predictions:

    • Solubility rules indicate which ionic compounds will dissolve in water.

    • Alkali metals, ammonium, nitrates, and acetates are usually soluble; carbonates, phosphates, sulfides, and hydroxides are not.

  • Ions Forming Soluble Compounds (with Exceptions):

    • Group 1 ions, ammonium, nitrates, acetates, hydrogen carbonate, chlorates, halides, sulfates (with specific exceptions).

  • Ions Forming Insoluble Compounds (with Exceptions):

    • Carbonates, chromates, phosphates, hydroxides, sulfides (with specific exceptions).

SOLUBILITY CURVES AND SATURATION

  • Saturated Solution: Contains maximum solute at a given temperature.

  • Unsaturated Solution: Contains less than maximum solute.

  • Supersaturated Solution: Contains more than maximum solute.

SUPERSATURATION

  • Adding a single crystal to a supersaturated solution leads to rapid crystallization.