Chapter 15 Solutions Homogeneous & Heterogeneous Aqueous System
Solution Also called homogeneous mixture – well evenly mixed of two or more substances (Ex) Gatorade, Koolade drink, metal alloys, carbonated drinks 1. Solute: the substance that dissolves or the substance in less amount 2. Solvent: the substance that does the dissolving or the substance in greater amount Can be liquid, solid, or gas
Factors Affecting Dissolving 1. Surface area – smaller particles dissolve faster than the larger particle of the same mass 2. Agitation – stirring speeds up dissolving 3. Heating - at higher temperature, particles move faster a) Less gas solute dissolved at higher temperature b) More solid solute dissolved at higher temperature 4.Pressure a) No affect on solid solute b) At higher pressure, more gas solute dissolved
Types of Solution based on Conductivity • Electrolytes: soluble ionic substances conduct electricity when dissolved in water (Ex) all compounds of 1A group, strong acids and bases such as NaCl(aq), HCl (aq) • Nonelectrolytes: nonpolar covalent substances that do not conduct electricity when dissolved in water (Ex) C12H22O11 (= sugar) • Weak electrolytes: polar covalent substances that somewhat conduct electricity when dissolved in water (Ex) weak acids and bases such as CH3COOH (=vinegar)
Solubility • General rule: “Like dissolves like” (1) Polar and ionic solute dissolves in polar solvent (Ex) NaCl dissolves in H2O (2) Nonpolar dissolves in nonpolar solvent (Ex) NaCl doesn’t dissolve in benzene, C6H6 • Measured in grams of solute dissolved in 100 g or 100 mL of solvent
How many grams of KCl dissolve in 100 g of water at 50 °C? How many grams of LiCl dissolve in 200 g of water at 40 °C? How many grams of LiCL dissolve in 50 g of water at 40 °C?
Types of Solution based on Solubility • Saturated solution: solution that contains the maximum amount of dissolved solute • Unsaturated solution: solution that contains less solute than a saturated solution • Supersaturated solution: solution that contains more dissolved solute than a saturated solution * Solubility of sugar at 25 ˚C = 91 g /100 mL water
Solute – Solvent Interactions • Use the rule: “Like dissolves like” (nonpolar solutes dissolve in nonpolar solvents and polar solutes dissolve in polar solvents Ex) oil (nonpolar) and water (polar): dissolves? Ex) salt (ionic) and water (polar): dissolves? • immiscible – one liquid doesn’t dissolve in another liquid (Ex) Oil (nonpolar) and water (polar) • miscible – one liquid dissolves in another liquid (Ex) ethanol (polar) in water (polar)