Chapter 13 Solutions

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

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

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

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

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

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

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

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

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

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

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

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

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