Do Now 2/6/15 1. What type of bond is being shown in the picture? 2. Why is the oxygen atom attracted to the hydrogen atom in water? 3. What are two characteristics that make water unique?

Agitation Agitation- stirring or shaking the mixture  Moves dissolved solute particles away from the contact surfaces  New collisions between solute and solvent particles

Surface Area Breaking down solute into small pieces increases its surface area GREATER surface area allows more collisions to occur

Teaspoon vs. Cube of Sugar

Temperature Hot temperatures dissolve solute FASTER Hotter solvents dissolve MORE solid solute

Pressure Increase pressure, increase gas solubility Gas particles are less soluble in hotter solutions because of increased molecular motion Changing temperature or pressure is how we achieve supersaturated solutions

Today I will be able to… Identify types of solutions:  electrolytes (strong and weak) and nonelectrolytes  Saturated, unsaturated, and supersaturated

Ionic Bonding Ionic Bond: chemical bond between a metal and nonmetal; electron(s) are transferred from the metal to the nonmetal

Ionic compounds are formed by these elements

Dissociation When a compound breaks down into its ions in a solvent. Ionic compounds completely dissociate in solution.

Covalent Bond Bond between two nonmetals Electrons are shared (two categories: polar and nonpolar covalent)

Types of bonds – it’s all about the electrons Nonpolar Covalent  Electrons are shared equally  bond between 2 identical nonmetals Polar Covalent  Electrons are not shared equally  One atom is more electronegative Ionic  Electrons are lost by one atom and gained by another (+ & - ions are formed)

Aqueous solution A compound (solute) dissolved in water (solvent) NaCl (aq)

Pure vs. Faucet

If water does not conduct electricity…..why the warning??

Electrolytes Solutes that dissolve in water to make a solution that conducts electricity. Substances that form ions in water are electrolytes. Light bulb test!

Strong Electrolytes they break apart in water so the solution conducts electricity Dissolves in solution COMPLETELY dissociates in solution Produce ions Example: NaCl  Na + (aq) + Cl - (aq)

Strong Electrolytes can be… Ionic compounds (metal and nonmetal)  Ex: BaCl 2 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: H 2 O + CH 3 COOH(l)  CH 3 COO - (aq) + H + (aq)

Weak Electrolytes SLIGHTLY dissociate in water Produce few ions, so their solutions are poor conductors of electricity. Written with a double arrow ( ⇌ ) Examples: tap water, NH 3, HNO 2, H 2 PO 4

How are weak electrolytes different from strong electrolytes? In weak electrolytes, the ions often join back together 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 in water as molecules instead of ions What is the difference between dissolving as a molecule and dissolving as an ion? Ex: H 2 O C 12 H 22 O 11 (s)  C 12 H 22 O 11 (aq)

Let’s look at them all together:

Categories Work with teammates Categorize compounds as either: electrolyte, nonelectrolyte, weak electrolyte, strong electrolyte Use the conductivity tester to check your answers!

Electrolytes Identify each as a strong, weak, or non-electrolyte HI CO 2 weak acid allows a strong current to pass through water KCl NH 4 Cl

Electrolytes Identify each as a strong, weak, or non-electrolyte HI - strong electrolyte CO 2 - nonelectrolyte weak acid – weak electrolyte allows a strong current to pass through water – strong electrolyte KCl – strong electrolyte NH 4 Cl – strong electrolyte

Sum it UP! What factors affect the strength of conductivity? Why are there electrical warnings on hairdryers when pure water does not conduct electricity?

Today I will be able to… Identify types of solutions:  electrolytes (strong and weak) and nonelectrolytes  Saturated, unsaturated, and supersaturated

Solubility Solubility is the ability to be dissolved. What factors affect solubility?

4 Factors that Affect Solvation Agitation Surface area Temperature Pressure

Solubility Curves Show how much solute can be dissolved under different conditions. a) How does temperature affect the solubility of NaNO 3 ? b) Temperature has the largest impact on the solubility of which substance?

Solubility Curves Show how much solute can be dissolved under different conditions. c) How much NaNO 3 can dissolve in 100 g H 2 O at 80 o C? d) How much KNO 3 can dissolve in 300 mL H 2 O at 40 o C?

Solubility Curves You Do – a. How much NaCl can dissolve in 100 mL water at 60 degrees C? b. How much KI dissolves in 50g water at 0 degrees C? c. Describe how temperature affects the solubility of KI.

Saturated vs. Unsaturated Solutions Saturated solutions contain the maximum amount of dissolved solute. If you try to add more solute to a saturated solution, it won’t dissolve. Unsaturated solutions contain less than the maximum amount of dissolved solute that can go into solution. If you add more solute to an unsaturated solution, it will dissolve.

Saturated vs. Unsaturated Solutions Supersaturated solutions contain more than the maximum amount of dissolved solute. How? Supersaturated solutions may form when a saturated solution is cooled and left undisturbed. As the solution cools, the solubility goes down. Usually, some solute will come out of solution as the temp goes down. Sometimes, solute will NOT come out of solution as temp goes down, resulting in a supersaturated solution

Saturated vs. Unsaturated Solutions Supersaturated solutions If a saturated solution of KNO 3 at 100 o C is cooled to 80 o C and none of the KNO 3 falls out of solution, the resulting solution will be supersaturated.

Saturated vs. Unsaturated Solutions Supersaturated solutions If a saturated solution of KNO 3 at 100 o C is cooled to 80 o C and none of the KNO 3 falls out of solution, the resulting solution will be supersaturated.

Saturated vs. Unsaturated Solutions Saturated, unsaturated, or supersaturated? 50 g of KNO 3 dissolved in 100 mL H 2 O at 60 o C 50 g of KNO 3 dissolved in 50 mL H 2 O at 40 o C 100 g of KNO 3 dissolved in 100 g H 2 O at 40 o C