II III I C. Johannesson I. The Nature of Solutions (p , ) Ch. 13 & 14 - Solutions

C. Johannesson A. Definitions  Solution -  Solution - homogeneous mixture Solvent Solvent – the dissolver (present in greater amount) Solute Solute - substance being dissolved

C. Johannesson A. Definitions Solute Solute - KMnO 4 Solvent Solvent - H 2 O

C. Johannesson B. Solvation  Solvation –  Solvation – the process of dissolving solute particles are separated and pulled into solution solute particles are surrounded by solvent particles

C. Johannesson B. Solvation Strong Electrolyte Non- Electrolyte solute exists as ions only - + salt - + sugar solute exists as molecules only - + acetic acid Weak Electrolyte solute exists as ions and molecules DISSOCIATIONIONIZATION View animation online.animation

C. Johannesson B. Solvation  Dissociation separation of an ionic solid into aqueous ions NaCl(s)  Na + (aq) + Cl – (aq)

C. Johannesson B. Solvation  Ionization breaking apart of some polar molecules into aqueous ions HNO 3 (aq) + H 2 O(l)  H 3 O + (aq) + NO 3 – (aq)

C. Johannesson B. Solvation  Molecular Solvation molecules stay intact C 6 H 12 O 6 (s)  C 6 H 12 O 6 (aq)

Ion number LPChem:Wz The number of ions created by a solute in solution is its “van’t Hoff factor.” NaCl  Na + + Cl - 2 ions!  This is often just called “ion number”  In equations it is the variable “i” o For NaCl, i = 2 o For BaCl 2, i = 3

LPChem:Wz B. Solvation Strong Electrolyte Non- Electrolyte Ionic compounds, Strong acids, Strong bases Molecular substances Weak Electrolyte Weak acids & Weak bases i = 1 1 < i < 2 i =2 or more

C. Johannesson B. Solvation NONPOLAR POLAR “Like Dissolves Like”

C. Johannesson B. Solvation  Surfactants bridge the gap Soap/Detergent:Soap/Detergent: polar “head” with long nonpolar “tail” dissolves nonpolar grease in polar water

C. Johannesson C. Solubility  Solubility Curve shows the dependence of solubility on temperature Most solid compounds are more soluble in water at higher temperatures

C. Johannesson C. Solubility  Solubility maximum grams of solute that will dissolve in 100 g of solvent at a given temperature varies with temp based on a saturated soln

C. Johannesson C. Solubility SATURATED SOLUTION no more solute can dissolve UNSATURATED SOLUTION more solute can dissolve SUPERSATURATED SOLUTION Unstable. crystals form if solute is added concentration

C. Johannesson C. Solubility  Solids are more soluble at... high temperatures.  Gases are more soluble at... low temperatures & high pressures (Henry’s Law). EX: nitrogen narcosis, the “bends,” soda

LPChem: Wz C. Solubility  How many grams of ammonium chloride can dissolve in 100 g of water at 50  C? 50. grams  If I add more than 50 g NH 4 Cl, the solution will be saturated.  If I add less, it is unsaturated.

LPChem: Wz C. Solubility  How many grams of SO 2 can dissolve in 50 g of water at 20  C? 5.5 grams (RATIO!)  Graph: 11g for 100 g H 2 O  11g/100g H 2 O = 5.5g/50g H 2 O