Do Now 2/6/15
1.What type of bondis being shown inthe picture?
2.Why is the oxygenatom attracted tothe hydrogen atomin water?
3.What are twocharacteristics thatmake waterunique?
Agitation
•Agitation- stirring or shaking the mixture
Moves dissolved solute particles away from thecontact surfaces
New collisions between solute and solvent particles
Surface Area
•Breaking down solute into small piecesincreases its surface area
•GREATER surface area allows morecollisions to occur
Teaspoon vs. Cube of Sugar
Temperature
•Hot temperatures dissolvesolute FASTER
•Hotter solvents dissolveMORE solid solute
Pressure
•Increase pressure, increase gas solubility
•Gas particles are less soluble in hottersolutions because of increased molecularmotion
Changing temperature or pressure is how weachieve supersaturated solutions
Today I will be able to…
•Identify types of solutions:
electrolytes (strong and weak)and nonelectrolytes
Saturated, unsaturated, andsupersaturated
Ionic Bonding
•Ionic Bond: chemical bondbetween a metal andnonmetal; electron(s) aretransferred from the metalto the nonmetal
Ionic compounds are formedby these elements
Dissociation
•When a compound breaks downinto its ions in a solvent.
•Ionic compounds
completely dissociate
in solution.
Covalent Bond
•Bond between twononmetals
•Electrons are shared
(two categories: polar andnonpolar covalent)
Types of bonds – it’s all about theelectrons
•Nonpolar Covalent
Electrons are sharedequally
bond between 2 identicalnonmetals
•Polar Covalent
Electrons are not sharedequally
One atom is more electronegative
•Ionic
Electrons are lost by one atom andgained by another (+ & - ions areformed)
Aqueous solution
•A compound (solute) dissolved in water (solvent)
•NaCl (aq)
Pure vs. Faucet
If water does not conductelectricity…..why the warning??
Electrolytes
Solutes that dissolve in water to make a solution thatconducts electricity.
Substances that form ions in water are electrolytes.
Light bulb test!Light bulb test!
Strong Electrolytes
•they break apart in water so the solution conductselectricity
•Dissolves in solution
•COMPLETELY dissociates in solution
•Produce ions
•Example: NaCl Na+(aq) + Cl-(aq)
Strong Electrolytes can be…
•Ionic compounds (metal andnonmetal)
Ex: BaCl2
•Strong acids (contains H+ ion)
Ex: HCl
•Strong bases (contains OH- ion)
Ex: NaOH
•Salts
Ex: NaCl
Strong Electrolytes
Strong electrolytes can only exist when they are in a solution.
These are both NaCl, table salt. Are they both strong electrolytes?
Weak Electrolytes
• Polar covalent compounds
• Weak acids
• Weak bases
Example: H2O + CH3COOH(l) CH3COO- (aq) + H+(aq)
Weak Electrolytes
•SLIGHTLY dissociate in water
•Produce few ions, so their solutions are poor conductorsof electricity.
•Written with a double arrow (⇌)
•Examples: tap water, NH3, HNO2, H2PO4
How are weak electrolytes differentfrom strong electrolytes?
In weak electrolytes, the ions often join backtogether to form a molecule
Nonelectrolytes
•Dissolve in a solvent
•DO NOT dissociate
•DO NOT conduct electricity
•Examples: sucrose (sugar), oxygen, sulfur dioxide,carbon dioxide, alcohols
Nonelectrolytes
Polar covalent substances that dissolve inwater as molecules instead of ions
What is the difference between dissolving asa molecule and dissolving as an ion?
Ex:
H2O
C12H22O11 (s) C12H22O11 (aq)
Let’s look at them all together:
Categories
•Work with teammates
•Categorize compounds as either:electrolyte, nonelectrolyte, weakelectrolyte, strong electrolyte
•Use the conductivity tester to check youranswers!
Electrolytes
Identify each as a strong, weak, or non-electrolyte
• HI
• CO2
• weak acid
• allows a strong current to pass through water
• KCl
• NH4Cl
Electrolytes
Identify each as a strong, weak, or non-electrolyte
• HI - strong electrolyte
• CO2 - nonelectrolyte
• weak acid – weak electrolyte
• allows a strong current to pass through water –strong electrolyte
• KCl – strong electrolyte
• NH4Cl – strong electrolyte
Sum it UP!
•What factors affect the strength ofconductivity?
•Why are there electrical warningson hairdryers when pure water doesnot conduct electricity?
Today I will be able to…
•Identify types of solutions:
electrolytes (strong and weak) andnonelectrolytes
Saturated, unsaturated, andsupersaturated
Solubility
Solubility is the ability tobe dissolved.Solubility is the ability tobe dissolved.
What factors affectsolubility?What factors affectsolubility?
4 Factors that Affect Solvation
•Agitation
•Surface area
•Temperature
•Pressure
Solubility Curves
Show how much solutecan be dissolved underdifferent conditions.
a)How does temperatureaffect the solubility ofNaNO3?
b)Temperature has thelargest impact on thesolubility of whichsubstance?
Solubility Curves
Show how much solutecan be dissolved underdifferent conditions.
c)How much NaNO3can dissolve in 100 gH2O at 80 o C?
d)How much KNO3 candissolve in 300 mL H2Oat 40oC?
Solubility Curves
You Do –
a.How much NaCl candissolve in 100 mLwater at 60 degreesC?
b.How much KIdissolves in 50gwater at 0 degrees C?
c.Describe howtemperature affectsthe solubility of KI.
Saturated vs. Unsaturated Solutions
Saturated solutions contain the maximum amount ofdissolved solute.
If you try to add more solute to a saturated solution,it won’t dissolve.
Unsaturated solutions contain less than themaximum amount of dissolved solute that can go intosolution.
If you add more solute to an unsaturated solution, itwill dissolve.
Saturated vs. Unsaturated Solutions
Supersaturated solutions contain more than themaximum amount of dissolved solute.
How?
Supersaturated solutions may form when asaturated solution is cooled and leftundisturbed.
•As the solution cools, the solubility goes down.
•Usually, some solute will come out of solution asthe temp goes down.
•Sometimes, solute will NOT come out of solution astemp goes down, resulting in a supersaturatedsolution
Saturated vs. Unsaturated Solutions
Supersaturated solutions
If a saturated solution of KNO3 at 100oC is cooledto 80oC and none of the KNO3 falls out of solution,the resulting solution will be supersaturated.
Saturated vs. Unsaturated Solutions
Supersaturated solutions
If a saturated solution of KNO3 at 100oC is cooledto 80oC and none of the KNO3 falls out of solution,the resulting solution will be supersaturated.
Saturated vs. Unsaturated Solutions
Saturated, unsaturated, or supersaturated?
•50 g of KNO3 dissolved in 100 mL H2O at 60oC
• 50 g of KNO3 dissolved in 50 mL H2O at 40oC
•100 g of KNO3 dissolved in 100 g H2O at 40o C