Unit 13: Solutions & Chemical Equilibrium Section 1: Properties of Solutions Solution Formation Rate of Dissolving Solubility

Can it be physically separated? Matter Flowchart MATTER yes no Can it be physically separated? MIXTURE PURE SUBSTANCE Is the composition uniform? no yes Can it be chemically decomposed? no yes Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element Colloids Suspensions

A. Solution Formation Solution - homogeneous mixture Solute - substance being dissolved Solvent – dissolving medium (dissolver)

A. Solution Formation Types of Solutions: Solute Solvent Example Gas Air (O2 & CO2 in Nitrogen) Liquid Water in Air Soda Vinegar (acetic acid in water) Solid Salt in water Stainless Steel (Cr & Ni in Iron)

A. Solution Formation Solvation The process of surrounding solute particles with solvent particles to form a solution Ionic compounds and polar covalent compounds undergo solvation in water (dissolve)

A. Solution Formation Water molecules surround the positive and negative ions, pulling them out of the crystal.

A. Solution Formation Solvation Process of Sucrose, C12H22O11 Water molecules H-bond with the O-H groups in sucrose, breaking the IMAF’s, and pulling the sucrose molecules apart

B. Rate of Dissolving Solids dissolve better... more stirring

B. Rate of Dissolving Solids dissolve better... more stirring more surface area (small particle size)

B. Rate of Dissolving Solids dissolve better... stirring more surface area (small particle size) high temp.

B. Rate of Dissolving Gases dissolve better... no stirring high pressure low temp.

Solubility in 100 g of Water at 20oC C. Solubility Solubility maximum grams of solute that will dissolve in an amount of solvent at a given temp. varies with temp. Solubility in 100 g of Water at 20oC Compound Solubility (g) Table Salt (NaCl) 36.0 Baking Soda (NaHCO3) 9.6 Table Sugar (C12H22O11) 203.9

C. Solubility Solubility Curve 1. What is the solubility of KCl at 70C? 50 g/100 g H2O 2. If you have 35 g of NaCl dissolved in 100 g of water at 70C, how many more grams can be dissolved? 5 g

Solubility Graph WS

less solute than max dissolved more than max solute dissolved C. Solubility UNSATURATED less solute than max dissolved SATURATED max solute dissolved SUPERSATURATED more than max solute dissolved concentration

less solute than max dissolved more than max solute dissolved C. Solubility UNSATURATED less solute than max dissolved SATURATED max solute dissolved SUPERSATURATED more than max solute dissolved Add a seed crystal concentration

less solute than max dissolved more than max solute dissolved C. Solubility UNSATURATED less solute than max dissolved SATURATED max solute dissolved SUPERSATURATED more than max solute dissolved concentration

less solute than max dissolved more than max solute dissolved C. Solubility UNSATURATED less solute than max dissolved SATURATED max solute dissolved SUPERSATURATED more than max solute dissolved Extra solute crystallizes concentration

D. 3 Factors Affecting Solubility Temp. Pressure high T: solids more soluble low T: gases more soluble high P: gases more soluble

D. 3 Factors Affecting Solubility Solvent Polarity: “Like Dissolves Like” H H H C C C H C C C C6H14 H H H H2O CCl4

D. 3 Factors Affecting Solubility Polar –Polar Polar –Nonpolar

Quick Quiz. 1) For a given substance, which of the following will NOT influence how fast it dissolves? A) temperature B) amount of agitation C) molar mass D) size of the crystals

Quick Quiz. 3) The solubility of a gas in a solvent is affected by? A) both temperature and pressure. B) only pressure C) only temperature D) your face

Quick Quiz. 4) Polar water molecules will NOT dissolve… A) polar alcohol molecules B) most ionic compounds C) nonpolar fat molecules D) partially ionized acetic acid molecules