SOLUTIONS

1
CHAPTER 16

• SOLUTIONS

2
Theme of the Chapter Solutions vs. Pure Liquids
3
Henrys law

• as the pressure of the gas above the liquid
  increases, so does the solubility of a gas in the
  liquid
• ex carbonated soda

4
Henrys Law

• As Pressure increases
• Solubility increases
• This is a direct proportion

5
Henrys Law

• ex 1 If the solubility of a gas in water is
  .77g/L at 350 kPa of pressure, what is the
  solubility, in grams per liter at 100 kPa of
  pressure?

6
Molarity

• 1. Tells how concentrated a solution is.
• 2. the of moles of solute dissolved in 1L of
  solution

7
(No Transcript)
8
Molarity

• ex1 How many moles of solute are present in 1.5L
  of .20M Na2SO4?
• -we are looking for moles of solute

9
How to Make Dilutions

• If you have a solution and the molarity is too
  high, you need to dilute the solution to lower
  the molarity (concentration).
• Use this equation to make a more dilute
  solutiion

10
How to Make Dilutions

• Ex 1 How would you prepare 200. mL of 0.60M
  MgSO4 from a stock solution of 3.0 M MgSO4?
• The dilute solution is 0.60M MgSO4, and we want
  to make 200.mL of it.
• The concentrated solution is 3.0M MgSO4.
• We need to remove some of this stock solution
  and then add some distilled water to it to dilute
  it. So, lets figure out how much distilled water
  to add.
• M1V1 M2V2 (200.mL)(.60M) (3.0M)(V2)
• V2 40mL therefore,
• 1. you would take 40mL of the stock solution
  (3.0M), and since we need 200mL,
• 2. you would add 160mL (200mL -40mL 160mL)
• of distilled water in order to make a
  .60M solution
• So, now we have 200.mL of our dilution 0.60M
  solution

11
How to Make Dilutions

1. Add 40 mL of stock to empty container
2. Add 160 mL of distilled water to empty
container (need 200mL, added 40 mL, need 160 mL
to top off)
stock solution 3.0M MgSO4
Dilute solution 0.60M MgSO4
12
Colligative Properties

• How are solutions different from pure liquids?
• When you add a solute to a liquid
• the
• Freezing point , Boiling point, and Vapor
  Pressure
• of the solution change

13
Colligative Properties

• Water The freezing point of pure water is 0C.
  The normal boiling point of water is 100C. But
  if you make a solution using water as the
  solvent, the freezing point of that solution will
  not be 0C nor will the boiling point be 100C.
• A SALT WATER SOLUTION
• The freezing point will be lower than 0C,
  boiling point will be higher than 100C, the
  vapor pressure will decrease.

14
Colligative Properties

• So
• 1. Freezing point depression
• 2. Boiling point elevation
• 3. Vapor pressure lowering

15
(No Transcript)
16
Vapor Pressure Lowering

• The pressure over a liquid or solution that
  results when molecules escape the liquid and
  enter the gaseous phase.
• In order for a molecule in the liquid phase to
  enter the gaseous phase, the molecule must be at
  the surface of the liquid and have enough kinetic
  energy to break the surface.  The addition of a
  nonvolatile hinders this situation in two ways
• The solute particles occupy space at the surface.
  
• The solute particles introduce a new set of
  attractive forces with the solvent molecules.

17

• The more dissolved solute the greater the
  changes.
• Ex the more salt you add to salt water the
  higher the Boiling Point, the lower the vapor
  pressure and freezing point
• Which will have a higher boiling point?
• 1M solution of CuCl2 vs. 1M solution C6H12O6

1M solution of CuCl2 Because there are more ions
in solution that hold onto the water molecules
18
Freezing Point Depression
19
Vapor Pressure Lowering