SOLVATION

							  SOLUTIONS AND
    SOLVATION

The Straight and Narrow Path to
           Solution
    The Day of Judgement
•   For You will be tested on 21 February
•   It is coming, You must be prepared.
•   You must know your solutions
•   You must know your Molarity
•   You must know your way to solve the
    problems
        MIXTURES VS
        COMPOUNDS
• Compounds: Chemically combined substances.
• Mixtures: Physically combined substances,
  normally made up of two or more compounds.
• Heterogeneous: Different Concentrations
  everywhere. It isn’t the same.
• Homogeneous: Exactly the same concentrations
  everywhere. It’s all the same everywhere.
           SOLVATION
• The process of dissolving a solute in a solvent
• Solutes: The material that is present in smaller
  amounts
• Solvents: The material that is present in the
  largest amount, can only be one in a solution
• And the Solvent said unto the Solute, “Come and
  be Dissolved by me!”
            NaCl(s)  Na+(aq) + Cl-(aq)
    What can be Solvated
• Soluble: The material can be dissolved.
• Insoluble: The material can’t be dissolved
• Miscible: A liquid that will dissolve
• Immiscible: A liquid that will not dissolve
• Solubility: How much can dissolve under
  the given conditions
• Alloy: A metal that is dissolved in another
  metal.
         Polar in Polar
• And the Like Molecules shall be dissolved
  by the Like Molecules, Polar unto Polar and
  Nonpolar unto Nonpolar each Unto it’s own
  kind
• Unlike Molecules shall not be dissolved by
  Unlike Molecules, Polar SHALL NOT
  dissolve Nonpolar, Oil and Water Shall Not
  dissolve.
 Common Polar Solvents
• Water: H2O
• Ammonia: NH3
• Ethanol: CH3OH
       Water is Polar
• As you can see, water has a positive
  side and a negative side.
                 The Process
• NaCl goes down into the Water

    The Water surrounds the NaCl pulling it
     apart, Na to the Negative side of water
     and Cl to the positive side of water and
     the NaCl is no more, it has been
     dissolved – it is one with the water.
     Polar unto Polar.
http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/molvie1.sw
   f
   NonPolar in NonPolar
• The NonPolar molecules become
  surrounded by the NonPolar
  Molecules, LIKE UNTO LIKE,
  surrounded the Nonpolar Solute is
  carried away as one with the
  Nonpolar Solvent.
       Common Nonpolar
          Solvents
•   Fats
•   Oil
•   Gasoline
•   Covalent Compounds
     Electrolytes versus
       Nonelectrolytes
• Electrolytes completely break apart
  and carry an electrical current. Polar
• Nonelectrolytes don’t break apart
  and don’t carry an electrical current.
  NonPolar
    Like Dissolves Like
• Polar substances are dissolved by
  Polar Substances
• Nonpolar substances are dissolved by
  Nonpolar Substances.
• Polar does not dissolve Nonpolar.
• Nonpolar does not dissolve polar.
Nonpolar will not dissolve
        in Polar
• Iodine is NonPolar, water is Polar, so
  it won’t dissolve
• Iodine will dissolve in Carbon Tetra
  Chloride which is NonPolar.
TYPES OF SOLUTIONS
• UNSATURATED: The solution can
  dissolve more solute.
• SATURATED: The solution cannot
  dissolve more solute.
• SUPERSATURATED: The solution
  has dissolved more solute then it
  should.
     UNSATURATED
• More can be added
        SATURATED
• The Solution cannot dissolve more:
    SUPERSATURATED
• The solution is holding more then it should.
• When more is added, a lot flows out.
 What a Supersaturated
      Looks Like
• http://www.amazingrust.com/experi
  ments/how_to/Hot-Ice.html
• http://www.wonderhowto.com/how-
  to-make-sodium-acetate-hot-ice-w-
  vinegar-baking-soda-274006/
       Supersaturated
      Sodium Acetate
• One application
  of a
  supersaturated
  solution is the
  sodium acetate
  “heat pack.”
     SUPERSATURATED
• HOW IT HAPPENS
• As a general rule: Solvents can hold a certain
  amount of Solute at a certain temperature
• If the temperature is raised, more solute can be
  dissolved.
• If the solution is then cooled, the solute stays
  dissolved.
• The solution is holding more solute then it should.
      How solutions are
         measured
• Concentration: How much solute there is
  in a given amount of Solvent.
• Molarity: Moles solute/Liters solution
• Molality: Moles solute/Kilograms solvent
• Mass Percent: grams solute/grams
  solution
     Concentration of
         Solute
 The amount of solute in a solution
  is given by its concentration.

                     moles solute
Molarity (M) =    liters of solution
 Properties of solutions
• Colligative property: A property that
  changes as a result of the solution
  being made
• Vapor Pressure Lowering: The vapor
  pressure of the solution goes down,
  the amount of substance release into
  the air goes down.
      More properties of
          solutions
• Boiling Point elevation: Boiling point of a solution
  is higher then that of just the solvent.
• Freezing Point depression: Freezing point of a
  solution is lower then that of just the solvent.
• Electrolyte: A substance in a solution that allows
  the solution to transmit an electric current
   Some Definitions
A solution is a mixture
  of 2 or more
  substances in a single
  phase.
One constituent is
  usually regarded as
  the SOLVENT and
  the others as
  SOLUTES.
            Parts of a Solution
• SOLUTE – the part
  of a solution that is
  being dissolved
                          Solut Solven         Example
                            e     t
  (usually the lesser
  amount)                 solid solid    Brass
• SOLVENT – the part
  of a solution that      solid liquid Tea, Coffee
  dissolves the solute    gas   solid    Foam
  (usually the greater
  amount)                 liquid liquid Ammonia
• Solute + Solvent =
  Solution                gas   liquid Carbonated
                                         Water
                          gas   gas      Air
       IONIC COMPOUNDS
  Compounds in Aqueous Solution

Many reactions involve ionic compounds,
 especially reactions in water —
 aqueous solutions.
  KMnO4 in water       K+(aq) + MnO4-(aq)
     Aqueous Solutions
How do we know ions are
 present in aqueous
 solutions?
The solutions conduct
 electricity
They are called
 ELECTROLYTES
HCl, MgCl2, and NaCl are
 strong electrolytes. They
 dissociate completely (or
 nearly so) into ions.
  Aqueous
  Solutions

Some compounds dissolve
  in water but do not
  conduct electricity.
  They are called
  nonelectrolytes.

 Examples include:
     sugar
     ethanol
     ethylene glycol
PROBLEM: Dissolve 5.00 g of NiCl2•6
H2O in enough water to make 250 mL of
solution. Calculate the Molarity.

Step 1: Calculate moles
of NiCl2•6H2O
          1 mol
5.00 g •         = 0.0210 mol
         237.7 g
Step 2: Calculate Molarity
 0.0210 mol
            = 0.0841 M
   0.250 L

[NiCl2•6 H2O ] = 0.0841 M
     USING MOLARITY
What mass of oxalic acid, H2C2O4, is
required to make 250. mL of a 0.0500 M
solution?
         moles = M•V
Step 1: Change mL to L.
250 mL * 1L/1000mL = 0.250 L
Step 2: Calculate.
Moles = (0.0500 mol/L) (0.250 L) = 0.0125 moles
Step 3: Convert moles to grams.
(0.0125 mol)(90.00 g/mol) = 1.13 g
           Learning Check
How many grams of NaOH are required to
prepare 400. mL of 3.0 M NaOH solution?

1) 12 g
2) 48 g
3) 300 g
Two Other Concentration
        Units
         MOLALITY, m
                      mol solute
 m of solution =
                 kilograms solvent


          % by mass


  % by mass =    grams solute
                 grams solution
              Calculating
            Concentrations
 Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g
 of H2O. Calculate m & % of ethylene glycol (by mass).

 Calculate molality
                  1.00 mol glycol
conc (molality) =                  4.00 molal
                   0.250 kg H2O
 Calculate weight %
               62.1 g
%glycol =                 x 100% = 19.9%
          62.1 g + 250. g
          Learning Check
A solution contains 15 g Na2CO3 and
235 g of H2O? What is the mass % of
the solution?
1) 15% Na2CO3
2) 6.4% Na2CO3
3) 6.0% Na2CO3
           Dilutions
• Stock Solution: A solution of known
  concentration, normally saturated,
  used to make other solutions.
• Diluting: Adding solvent to make a
  reduce the concentration of a
  solution.
     Dilution Equation
• M1V1 = M2V2
• Mr Simms needs 250 mL of 0.150 M
  CuCl2 Solution. He has 3.00 M Stock
  Solution. How much of the stock
  solution does he need to use?
         Problem Set up
•   M1V1 = M2V2
•   M1 = 0.150 M
•   V1 = 250 mL
•   M2 = 3.00 M
•   V2 = X mL
                Answer
•   (0.150 M)(250 mL) = (3.00 M)X
•   (0.150 M)(250 mL) = X
•   (3.00 M)
•   X = 12.5 mL
•   Explanation: I need to start with 12.5 mL
    of 3.00M Stock Solution and dilute it to
    250 mL by adding 237.5 mL of Water.
   Boiling Point Elevation
 DT = (# ions)(molality)Kb
 DT = Change in Temperature, not new
  Temperature
• (# ions) = Number of ions, NaCl has 2, MgCl2 =
  3, All Covalent compounds are 1.
• Molality = You should know this already
• Kb = a Boiling point constant for the Solvent
            Example
• What is the new boiling point for a
  1.20 molal solution of NaI?
 DT = (# ions)(molality)Kb
• # ions = 2
• Molality = 1.20 molal
• Kb for water = 0.512 C/m
     Example continued
 DT = (# ions)(molality)Kb
 DT = (2)(1.20)(0.512)
 DT = 1.23 C
• Old Boiling point = 100
• New Boiling point = 101.23
         Freezing Point
          Depression
• What would the new Freezing point of the
  solution be?
 DT = (# ions)(molality)Kf
• Kf for water is 1.86 C/m
 DT = (2 ions)(1.2 m)(1.86 C/m)
 DT = 4.46 C
• Old Freezing point of water = 0
• New Freezing point of water = 0 – 4.46 = -4.46 C