CHAPTER 15: SOLUTIONSHonors Chemistry

SOLUTIONS• A solution is a

• The is(are) the substance(s) present in the

• The is the substance present in the

AQUEOUS SOLUTIONS• Solutions with

SOLVATION• The process by which an

is surrounded by solvent molecules arranged in a specific manner

• This

MISCIBLE VS. IMMISCIBLE• Miscible: liquids that

• Immiscible: liquids that

“LIKE DISSOLVES LIKE”• Two substances with similar

are likely to be in each other

• Non-polar molecules are soluble in–Ex.:

• Polar molecules are soluble in–Ex.:

• Ionic compounds are more soluble in–Ex.:

SOLUTION SATURATION• Saturated solution: contains the

amt. of a solute that will dissolve in a given amt. of solvent at

• Unsaturated solution: contains solute than a solvent has the capacity to dissolve at

• Supersaturated solution contains solute than is present in a saturated solution at

NaC2H3O2 crystals form when a seed crystal is added to a of NaC2H3O2

SOLUBILITY• Measure of how much

FACTORS AFFECTING SOLUBILITY1. Temperature: solubility of solids

and liquids generally • The solubility of gases generally

2. Pressure: solids and liquids are

• The solubility of a

(Henry’s LawHenry’s Law)

CONCENTRATION OF SOLUTIONS• The of a solution is

the amt. of solute present in a given quantity of solvent or solution

• Concentrated: (qualitative observation)

• Dilute: (qualitative observation)

• Standard Solution: a solution whose

CONCENTRATION UNITS• Quantitative measurements…

• Mass Percent:

CONCENTRATION UNITS• Molarity ( ): moles of solute per

liter solution ( )

• Molality ( ): moles of solute per kg solvent ( )

2 WAYS TO QUANTIFY RATIO OF SOLUTE PARTICLES TO SOLVENT• Molality, or molal concentration,

(m)–m =

• Mole fraction

DILUTIONS• Stock solutions: concentrated

solutions that are purchased or prepared to save time and space in the lab

• Solvent can be added to a to achieve a desired concentration to be used for a specific purpose

• Dilution:

COLLIGATIVE PROPERTIES OF SOLUTIONS• Colligative properties:

• Solutes that dissociate (i.e. ) have a greater effect than those that do not

• Ex.: 1 mol of MgCl2 would have more effect than 1 mol of NaCl which has more effect than 1 mol of glucose (C6H12O6). Why?!

3 COLLIGATIVE PROPERTIES1. -

2. -

3. -

DECREASE IN VAPOR PRESSURE• The addition of solute to a

solvent lowers the vapor pressure of the solvent

• Why?–Solvent particles surround solute

particles, which reduces the solvent’s kinetic energy

–Now solvent can’t “shoot out” into gas as often

BOILING POINT ELEVATION• The addition of solute to a solvent

raises the boiling point of the solvent

• Why?–Vapor pressure is reduced. More

heat is required to break intermolecular forces holding solvent in liquid phase

–NaCl in H2O when cooking pasta

FREEZING POINT DEPRESSION• The addition of solute lowers

the freezing point of the solvent

• Why?–Solute disrupts the organized

freezing pattern of the solvent

–Salt on icy roads