Chapter 13. Characteristics of a Solution. Example of A Homogenous Mixtures. Solutions

Transcription

1 Chapter 13 Solutions Characteristics of a Solution A solution is a homogeneous mixture A solution is composed of a: Solute: the substance in lesser amount Solvent: the substance in greater amount Two liquid mixed together may be: Miscible: they dissolve in each other Immiscible: they do not dissolve in each other Example of A Homogenous Mixtures Solution of NaCl Solvent Water Solute Na + ions Cl ions 1

2 Example of A Homogenous Mixtures Interaction is happening in a solution at a submicroscopic level. Terms for Concentration Concentrated: A relativity large amount of solute in the solvent Dilute: A relativity small amount of solute in the solvent Solubility: A measure of how much solute will dissolve in a given solvent Terms for Concentration Saturated: The maximum amount of solute that will dissolve Unsaturated: Less than the maximum amount of solute Supersaturated: More than the maximum amount of solute Unstable 2

3 Terms for Concentration Electrolyte solutions conducts an electrical current Strong electrolyte solution strongly conducts electrical current Weak electrolyte solution weakly conducts electrical current Nonelectrolyte solution does not conduct an electrical current Numeric Concentration Units Percent: Parts per 100 Mass percent Volume percent Mass / volume percent Numeric Concentration Units Molarity (M): Moles of solute per liter of solution (mol/l) Molality (m): Moles of solute per kilogram of solvent (mol/kg) 3

4 Molarity: How to Prepare a solution 1 Liter of 1.0 M NaCl Add 1.0 mol (58.4 g) of NaCl Dilute to 1 Liter with water The Formation of a Water Solution The water molecules the solid is then hydrated The more alike the forces of attraction are When a solution forms: There are many factors that effect the formation of a solution. 4

5 Factors for How Much: Intermolecular forces: Polar and Ionic solutes are usually soluble in polar solvents. Non-polar solutes are usually soluble in nonpolar solvent. Polar and non-polar usually does not mix Factors for How Much: Partial Pressure: Only effect the solubility of a gas in a liquid Increase the pressure and the solubility increases Factors for How Much: Temperature For solids in liquids: For gases in liquids 5

6 Factors for How Fast Stirring: Stirring will increase the rate of solubility Stirring will not change the how much will dissolve just how fast it will dissolve Size of the Particle: The larger the particle the slower the solubility Small particles dissolve faster than larger ones Solution Dilution Stock Solutions Dilutions Made from Stock Solution Lower Molarity M 1 V 1 = M 2 V 2 M 1 Initial Molarity V 1 Initial Volume M 2 Final Molarity V 2 Final Volume Solution Stoichiometry Chemical Reactions in Aqueous Solution Types of Reactions Precipitation Neutralization Gas Evolution Stoichiometry Balanced Chemical Equations Mathematical Relationship between the Reactants and Products 6

7 Freezing Point Depression and Boiling Point Elevation Colligative Properties Depend on the Number of Solute Particles in Solution Not Type of Particles Freezing Point Depression Freezing Point Depression The freezing point of a solution containing a nonvolatile solute is lower than the freezing point of the pure solvent. The more concentrated the solution, the lower the freezing point Concentration m Molality Moles of Solute divided by Kilograms of Solvent Boiling Point Elevation Boiling Point Elevation The boiling point of a solution containing a nonvolatile solute is higher than the boiling point of the pure solvent. Antifreeze Prevents Freezing of Water in Cold Climates Boiling of Water in Hot Climates 7

8 Osmosis Osmosis The flow of solvent from a lower concentration solution to a higher concentration solution. 8