Solutions!

Classification of Matter

Mixtures = a physical blend of 2 or more components 2 types: (1) Homogenous Mixture = ____________________________ - Homogenous Aqueous Mixture: ________________ (2) Heterogenous Mixture = ____________________________ - Heterogenous Aqueous Mixtures: Suspensions Colloids

Separating Physical Mixtures 1.) Filtration =______________________________________________________ ______________________________________________________

2.) Distillation =_________________________________________________________________________________________________________ 3.) Chromatography = __________________________________ __________________________________

Solutions = a homogenous mixture of substances in the same physical state **We will be discussing aqueous solutions mostly.** ___________________ Solvent =_______________________ Solute = _______________________  can be atoms, ions, or molecules **Remember: Ionic compounds & polar compounds will dissolve readily in water. Nonpolar covalent compounds will not.

How do solutions form? When an ionic compound dissolves in water: http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/thermochem/solutionSalt.html When an ionic compound dissolves in water: **solvation = _________________________________________ http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/molvie1.swf

“_____ dissolves ____!” Polar compounds can also readily dissolve in water. Nonpolar compounds cannot dissolve in water.  Why not? **But….nonpolar compounds can dissolve in ___________ solvents. “_____ dissolves ____!” ________ compounds will dissolve in a polar solvent, but not a nonpolar solvent. ________ compounds will dissolve in a polar solvent, but not a nonpolar solvent. __________ compounds will dissolved in a nonpolar solvent, but not a polar solvent.

Electrolyte = ________________________________________ _________________________________________ **All ionic compounds are electrolytes because: ________________________________________ Nonelectrolyte = _________________________________________ **Most compounds are nonelectrolytes because:

Factors Affecting How Fast Particles Dissolve 1.) Stirring makes compounds dissolve faster. 2.) Higher temperatures make compounds dissolve faster. 3.) Smaller-sized particles dissolve faster.

Solubility Solubility = ___________________________________________ - usually expressed in grams of solute per 100g of solvent Factors Affecting Solubility 1.) Nature of solute & solvent: **Remember: “Like dissolves like.”**

2.) Temperature: - As temperature , most solids become ____ soluble in water. - As temperature , most gases become ____ soluble in water. 3.) Pressure: - Pressure has little to no effect on solubility of liquids & solids. - As pressure , solubility of gases in liquids ______

Solubility Curve Shows the relationship of grams of solute that may be dissolved at various temperatures. Each line represents the maximum amount of that substance that can be dissolved at a given temperature. Lines show an increase in the solubility of solids as temperature increases, and a decrease in the solubility of gases as temperature increases.

Unsaturated Solution: = contains the maximum amount of solute for a given quantity of solvent at a constant temperature & pressure  if additional solute is added, it will not dissolve; rather it will precipitate out Unsaturated Solution: = a solution that contains less solute than a saturated solution at a given temperature & pressure  if additional solute is added, it will dissolve Supersaturated Solution: = contains more solute than it can theoretically hold at a given temperature  crystallization will be initiate if a very small “seed crystal” of solute is added **very unstable** Sample Individual Solubility Curve- Potassium nitrite http://www.metacafe.com/watch/404010/rapid_crystallization_supersaturated_solution_demo/

Colligative Properties of Solutions Colligative Property = ________________________ ________________________  Vapor Pressure Lowering  Boiling Point Elevation  Freezing Point Depression

Vapor Pressure Lowering Remember: Vapor pressure = __________________________________ **A solution always has a lower vapor pressure than the pure solvent.** Why??

Boiling Point Elevation Remember: A low vapor pressure means more energy is needed to get the substance to boiling (vapor pressure = atmospheric pressure). So….. **A solution always has a higher boiling point than the pure solvent.**

Freezing Point Depression **A solution always has a lower freezing point than the pure solvent.** Why??? Vs.

The magnitude of a colligative property change is proportional to the # of solute particles dissolved in the solvent. So, the greater the # of particles:  the lower the vapor pressure goes  the higher the boiling point goes  the lower the freezing point goes Ionic solids, therefore, produce a greater change in colligative properties: C6H12O6 (s)  C6H12O6 (aq) NaCl (s)  Na+(aq) + Cl-(aq) CaCl2(s)  Ca +(aq) + 2Cl-(aq)