Solutions

1
Solutions

• Ch.12 13

2
Liquids
3
Condensed States

• Liquids and Solids
• Higher densities
• Slightly compressible
• Slow diffusion(mixing)
• Physical state depends on strength of attraction
  between particles

4

• Gases weak forces of attraction
• Liquids stronger forces
• Solids really strong forces
• Forces of attraction? intermolecular forces

5
Properties of Liquids

• Viscosity
• Friction, resistance to motion
• syrup vs. water
• Stronger intermolecular forces
• greater viscosity
• Low temperatures
• greater viscosity

6
Properties of Liquids

• Surface Tension
• Tight film on surface of water
• Uneven forces at surface
• Causes rain to fall in drops!
• Video - 30

7
Solutions
8
Properties of Solutions

• Homogenous mixtures
• Particles are very small
• Particles mixed evenly
• Particles will not separate
• Made of solute (gets dissolved) and solvent (does
  the dissolving)

9
Properties of Solutions

• Soluble - substance dissolves in another
  substance
• Insoluble substance does NOT dissolve

10
Types of Solutions

• Solid Solutions
• Alloys mixture of 2 or more metals
• Melting the metals, mixing and cooling
• Sterling silver silver and copper
• Gaseous Solutions
• Mixture of gases (air)

11
Types of Solutions

• Liquid Solutions
• Solvent and Solution are liquids
• Solute solid, liq. or gas
• Mixing liquids
• Miscible liquids that mix thoroughly
• Immiscible liquids that cannot mix

12
Types of Solutions

• Aqueous Solutions
• Water is universal solvent
• Ionic compounds dissolve to give ions
• Solution conducts electricity - electrolyte
• Solutions that do not - nonelectrolyte

13
Solubility

• Ch.12 Section 2

14
Solubility

• Def amount of solute that will dissolve in a
  specific solvent
• Temp. and Pressure(gas) given with solubility
• Solubility can be altered by
• Type of Solvent (Polar/Nonpolar)
• Surface area of solute particles
• Molar Mass of solute or solvent
• Pressure
• Temperature of solvent

15
Type of Solvent

• Like dissolves like
• Water is polar ? will only dissolve polar solutes
• Paint thinner and gasoline are nonpolar
• SOAP universal polar and nonpolar ends

16
Surface Area

• Solvents can only dissolve the surface of the
  solute particles
• Smaller particles dissolve faster
• Stirring also increases of collisions

17
Mass of Solute or Solvent

• A large molar mass SOLUTE will need more energy
  to break up particles
• A large molar mass SOLVENT has more energy to
  break up solute

18
Pressure

• Mainly affects solubility of gas solutes
• Henrys Law solubility of gas is directly
  proportional to partial pressure of the gas on
  the liquid.
• Video - 48

19
Temperature

• Higher temp. faster particles harder
  collisions smaller particles
• Allows solute to mix in with solvent faster

20
Heats of Solution

• Energy is involved in forming solutions
• Endothermic rxn a rxn that absorbs heat (feels
  cold)
• Exothermic rxn a rxn that gives off heat (feels
  warm)

21
Saturation

• Limit to amount of solute that can be dissolved
  in solvent
• A solution is saturated when no more solute can
  be dissolved - reached equilibrium
• Add more solute and doesnt dissolve

22
Saturation

• Unsaturated solution has less than the max amount
  of solute that can be dissolved
• Supersaturated solution has a greater amount of
  solute than needed to get a saturated solution

23
Concentration

• Ch.12 Section 3

24
Concentration of Solutions

• Concentration amount of solute in a given amount
  of solvent or solution
• Concentrated a lot of solute in solvent
• Dilute small amt of solute in solvent

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Concentration of Solutions

• Most common unit is Molarity (M)
• M moles of solute
• liters of solution

26
Molarity Examples

• What is the molarity of a .100 L solution of NaOH
  if 10.0 g of NaOH were dissolved?
• How many grams of CaCl2 are needed to make a 1.00
  M solution?
• What volume is required to make a 3.0 M with 5.50
  mol NaCl?

27
Making Solutions

• How would you make 250 mL of 6.00 M NaOH
  solution?

28
Concentration of Solutions

• Molality (m)
• m moles of solute
• kilograms of solvent
• What is the molality of a solution if 18.0 g
  C6H12O6 (180. g/mol) is dissolved in 3.0 x 103 g
  of water?

29
Solution Stoichiometry

• Limiting Reactant is Back!

30
Solution Stoichiometry

• Mix 2 aqueous solns a rxn could occur
• If rxn occurs, get precipitate
• Limiting Reactant controls amt of product
• BUT NOW
• Our reactants are not solids, we have AQUEOUS
  SOLUTIONS
• How do we get moles of our reactants?

31
Getting Moles of Reactants

• Aqueous solutions are given in MOLARITY.
• Ex 6 M 6 moles of solute
• 1 L of soln
• Get Moles from Molarity!!

32
Example

• Zn(NO3)2(aq) Na2CO3(aq) ? ZnCO3(s)
  NaNO3(aq)
• What mass of ppt can be formed when 50.0 mL of
  2.0 M Zn(NO3)2 reacts with 35.0 mL of 2.0 M
  Na2CO3?
• Write balanced equation
• Find moles of each reactant
• Convert moles of reactant ? moles of ppt ? mass
  of ppt

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Examples

• 0.55 g of ppt, Cu(OH)2 is formed when excess
  CuSO4 solution is mixed with 75.0 mL of NaOH
  solution. What is the concentration of NaOH?
• Write balanced equation
• Find moles of NaOH
• Calculate Molarity

34
Examples

• What volume of 0.500 M HBr is required to react
  with 250 mL of 1.00 M NaOH?
• Balanced Equation
• Find Moles NaOH ? moles HBr
• Use moles HBr ? L of HBr

35
Changing Concentration
36
Changing Concentration

• Add more solvent
• Diluting the solution
• Less concentrated solution
• Decrease solvent/ Add solute
• Evaporation of solvent
• Adding more solute
• More concentrated solution

37
DILUTION

• Only use dilution when need concentration LESS
  THAN what you start with
• MoVo MnVn
• M molarity of total solution
• V volume of total solution
• Concentration has to be in molarity
• Volume units just have to be the same!

38
MoVo MnVn

• You have 25.0 mL of a 10.0 M solution of NaCl.
  You only need it to be 2.50 M. What must your
  volume be to make this solution?
• How much water do you need to add?

39
Ionic Reactions in Solutions

• Ch. 13

40
Ionic Solutions

• When water dissolves the solute, the ions of
  solute are hydrated
• Ionic crystals that trap water with in
  themselves are hydrates
• Ex CuSO4 5H2O
• Copper(II) sulfate pentahydrate

41
Ionic Solutions

• Dissociation when ions separate
• NaCl(s) ? Na1(aq) Cl-(aq)
• If 1 mole of NaCl dissolves then 1 mole of each
  ion produced
• Remember Molar Ratios!!!
• CaCl2(s) ? Ca2(aq) 2Cl-(aq)
• 1 mol 1 mol 2 mol

H2O
H2O
42
Ionic Solutions

• Not all ionic compounds are soluble in water
• Table of Solubility Rules!
• Can determine whether a compound will dissolve
• Soluble or Insoluble in water?
• Copper(II) carbonate
• Sodium hydroxide
• Silver chloride
• Potassium sulfate

43
Double-Replacement Rxns

• AX BY ? AY BX
• Mix two aqueous ionic solutions
• NaI(aq) Pb(NO3)2(aq) ?
• Products and their phases?
• The solid formed during a reaction is the
  precipitate

44
Net Ionic Equations

• Def An equation that shows only those compounds
  and ions that undergo a chemical change.
• Ions that do not take part in the chemical
  reaction and are found in the solution before and
  after the reaction are spectator ions.

45
Net Ionic Equations

• Rubidium phosphate Titanium(IV) nitrate
• Ammonium sulfate magnesium chloride
• Calcium hydroxide Cobalt(II) acetate

46

• Write the Complete ionic equation, the Net Ionic
  Equation and list the spectator ions for the
  following aqueous solutions
• Rubidium hydroxide hydrochloric acid
• Ammonium nitrate Cesium phosphate
• Boron sulfate Potassium hydroxide
• Strontium chloride Lead(II) nitrate