Types of Mixtures and Solution Processes

1. Chapter 13 Solutions

2. Sect. 13-1: Types of Mixtures • Solution – homogeneous mixture of 2 or more substances with small particle size • Made up of solute (substance being dissolved) and solvent (substance doing the dissolving) • Soluble – can be dissolved • Suspension – a heterogeneous mixture of which the relatively large particles will settle out unless continually stirred • Colloid – heterogeneous mixture with particle size between solutions and suspensions

3. Tyndall effect • Used to distinguish between colloids and solutions • Particles in a colloid are large enough that they scatter light as it passes through

4. Electrolyte – substance that when dissolved in water to form a solution will conduct electricity • Non-electrolyte – substance that when dissolved in water to form a solution will not conduct electricity

5. Sect. 13-2: The Solution Process • Factors affecting rate of dissolving: • Increasing surface area of solute • Agitating solution • Heating the solvent

6. Solution equilibrium – physical state in which the dissolving and crystallization of the solute occur in equal rates • Saturated solution – contains maximum amount of solute • Unsaturated solution – contains less than the saturated solution at a given set of conditions • Supersaturated solution – contains more dissolved solute than a saturated solution contains under a given set of conditions

7. Solubility – the amount of a substance required to form a saturated solution with a specific amount of solvent at a specified temperature

8. Solute – Solvent Interactions • “like dissolves like” • During dissolving of ionic compounds, ions are surrounded by the solvent particles and pulled away from the rest of the crystal • Hydration – solution process with water as the solvent • Hydrates have water molecules incorporated in their structures • Ionic compounds are generally not soluble in non-polar solvents

9. Immiscible – liquid solute & solvent that are not soluble in each other • Miscible – liquids that are soluble in each other

10. An increase in pressure increases gas solubility • Henry’s law – solubility of a gas in liquid is directly proportional to the partial pressure of the gas on the surface of the liquid • Effervescence – rapid escape of gas from liquid in which it was dissolved

11. Generally an increase in temperature causes an increase in solubility of a solid in a liquid • An increase in temperature causes a decrease in solubility of a gas in a liquid • See graphs on pg. 408

12. When a solute particle is surround by solvent particles it is said to be Solvated • Heat of solution – the net amount of heat energy absorbed or released when a specific amount of solute dissolves in a solvent • Negative value when heat is released • Positive value when heat is absorbed

13. Sect. 13-3: Concentration of Solutions • Concentration – measure of the amount of solute in a given amount of solvent or solution • Molarity – number of moles of solute dissolved in one liter of solution • Molality – number of moles of solute dissolved per kilogram of solvent

14. Formulas… • Molarity (M) = moles solute liters of solution • Molality (m) = moles solute kg of solvent