Chpt 9: Solutions

1
Chpt 9 Solutions

• Water
• Solutions
• Electrolytes
• Equivalents
• Solubility
• Percent Concentration
• Colloids Suspensions
• Osmosis
• Dialysis

2
Hydrogen Bonding of Water
Polar Attraction
Hydrogen Bonds
3
Hydrogen Bonding of Water
Hydrogen Bonds
Causes Surface Tension
Surfactants reduce Surface Tension by disrupting
H-bonding (soaps, detergents etc.)
4
Hydrogen Bonding of Water

Frozen H2O Slow moving molecules H-Bond in
patterns (Hexagonal Ring Crystals)
5
Hydrogen Bonding of Water

Solute particles interfere, causing the water
molecules to slow down even more. This reduces
the temperature.
6
Solutions
A solution A homogeneous mixture components.
Sugar in water Saline Oxygen in water Air Dental
fillings
7
Solutions

• Solvent
• component in greater amount
• (The dissolver)
• Water
• Alcohol

• Solute
• component in lesser amount
• (The dissolved)
• NaCl
• Sugar

8
Solutions

• solute evenly dispersed

• always stays mixed

• the solute cant be filtered out

• particles are always in motion

• volumes not additive

9
Solutions
Gaseous solutions Air, Anesthesia gases
Liquid solutions
Soda, Vodka, Saline,
Solid solutions dental fillings, 14K gold (58
Au ), Brass (Zn in Cu), Steel (C in Fe),
10
Hydration
Polar water attracts to Na and Cl- ions
Like Dissolves Like
When an ionic solid dissolves in water, the polar
solvent removes ions from the crystal lattice.
11
Hydration
12
Hydration
13
Hydration
14
Hydration
15
Hydration
16
Hydration
17
Hydration
18
Hydration
19
Hydration
20
Hydration
Like Dissolves Like
21
Hydrates
Copper (II) sulfate pentahydrate (Blue)
D
5H2O
Water of Hydration
Copper (II) sulfate (White)
Copper (II) sulfate hemihydrate (Plaster
of Paris for casts)
2H2O
CaCl2
Calcium chloride (drying agent attracts
water)
22
Dissolving covalent compounds

• Covalent compounds do not dissociate.

23
Electrolytes
Ionic
Covalent
No Ions
Dissolved Ions
NaCl ? Na Cl-
24
Electrolytes
Ionic
Weak
Strong
Lots of Ions
Only a few Ions
NaCl ? Na Cl-
HF ?? H F-
25
Electrolytes

• Electrolytes
• ionic compounds that form ions in polar solvents
• conduct electricity
• may be strong (100 dissociation) or weak (less
  than 100)

• When ionic materials dissolve in water -
• they dissociate
• we show them as ions
• NaCl(s) Na(aq)
  Cl-(aq)
• we can then call 1 M NaCl
• 1 eq/L Na and 1 eq/L Cl-
• 1 M NaCl 2 M ions

Often used in medicine
26
Ions in our blood are often compared to each
other in terms of their charges. ex. 1 mole of
charge is always equivalent to another mole
of charge. In terms of charges
1 mole Na 1 mole K
or 1 mole Ca2 2 moles Na
An equivalent (eq) refers to avogadro's number.
If there is 1 eq/L of Na, then there is
avogadro's number of sodium ions (6.02 x 1023) in
the solution. One mole of any ion with a 1
charge would be equivalent. Sometimes we focus
on the total amount of charge, not the specific
ion that carries it. If an ion has a 2 charge,
than it would only take 1/2 a mole to give 1
equivalent of charge. (ex. Ca2)
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Electrolytes in Blood
Serum Electrolytes Eq/mol sodium Na1
1 potassium K1 1 calcium Ca2
2 magnesium Mg2 2 chloride Cl1-
1 Sulfate SO42- 2 Phosphate
PO43- 3
Equivalent mols of charge
Liter
28
Electrolytes in Blood
Equivalent mols of charge
Liter
How many Eq from 6.0 g of Ca2?
6.0g Ca2 1 mol Ca 2 40.1g Ca
2
0.30 Eq Ca 2
2 mol charge 1 mol Ca 2
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Electrolytes in Blood
Serum Electrolytes meq/l sodium Na1
135 - 145 potassium K1 3.5 -
5.0 calcium Ca2 4.5 - 5.5 magnesium Mg2
1.5 - 2.5 chloride Cl1- 95 -
105 bicarbonate, HCO31- venous 19 -
25 arterial 22 - 26
1000 mEq 1 Eq
30
Saturation
Unsaturated Can dissolve more.
Saturated Have dissolved all possible
Undissolved Solids in equilibrium w/ dissolved
particles
31
Saturation
Supersaturated Temporarily dissolves more
than normal at given Temp.
Precipitate Excess solute that falls out of
solution
32
Solubility
How much solute will dissolve in a solvent
grams solute mls solution

• Factors affecting solubility
• Polarity
• Temperature
• Pressure

33
Polarity vs Solubility
Like Dissolves Like
Polar Attracts Polar
Nonpolar Attracts Nonpolar
NaCl dissolves in H2O But not in C6H14
Oil dissolves in C6H14 But not in H2O
34
Temperature vs Solubility
Gas
NaCl
Solubility (g/100ml water)
Temperature (oC)
35
Temperature vs Solubility
when T increases
Sol
T
Solids more soluble

• Gases most liquids less soluble

T
Sol
36
Temperature vs Solubility
The solubility of a gas in a liquid is inversely
related to the temperature .
If T goes up
Gas solubility goes down (gases escape)
Gas Solubility
37
Temperature vs Solubility
Carbonated beverages bottled cold.
Divers with bends often packed in ice for
transport to hyperbaric chamber.
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Temperature vs Solubility
Cold H2O holds more gas than warm H2O
If hot rivers lose too much dissolved O2 the
fish cant survive.
39
Pressure vs Solubility
when P increases
Solids Liquids unaffected

• Gases
• More soluble

Sol
P
40
HENRYS LAW
The solubility of a gas in a liquid is directly
related to the pressure on the liquid.
Gas solubility goes up (more gas will dissolve)
If P goes up
41
HENRYS LAW
If P goes down
Gas solubility goes down (gases escape)
Example opening a soda.
Soda under high pressure
Soda under low pressure
42
The Bends
Lower P
Less dissolved gases
Quick ascent Get bubbles in blood joints ?
extreme pain
High P
Lots of dissolved N2
43
The Bends
Lower P
N2 accumulates in brain, spinal cord, and
peripheral nerves. Bubbles here can cause
paralysis and convulsions. Effects often
irreversible.
Less dissolved gases
High P
Lots of dissolved gases
44
Solubility











NO31-
Cl1-
SO42-
Li1 Na1 K1 NH41
Ca2 Sr2 Ba2
S S S
S S S
Pb2 Ag1 Hg22
I I I
S S S
45
Concentration of solutions
How much solute is in a solution

• Percent

mass percent m/m mass
g solute 100 g solution
ml solute 100 ml solution
Volume percent v/v volume
mass percent m/v volume
g solute 100 ml solution

• Molarity M

46
Mass/Volume
If 5 grams of NaCl is dissolved in water to make
200 ml of solution, what is the concentration?
5 g NaCl 200 ml sln
2.5 m v
g solute 100 ml solution
2.5
x 100 100
Mass solute x 100 m/v Total Volume
Part x 100 Whole
Saline is a 0.9 m solution of NaCl in water.
v
47
Volume/Volume
If 10 ml of alcohol is dissolved in water to make
200 ml of solution, what is the concentration?
Volume solute Total Volume
x 100
Part Whole
x 100
10 ml alc x 100 200 ml sln
5 v v
Alcohol in beverages measured as v v
48
Mass/Mass
If a ham contained 5 grams of fat in 200 g of
ham, what is the m/m ?
Mass solute Total Mass
x 100
Part Whole
x 100
5 g fat x 100 200 g ham
2.5 m m
On the label, it would say 97.5 fat free
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as Conversion Factor

• How many grams of glucose does it take to make
  2.00 L of a 5 m/v Glucose solution.

g Glu
2.00 L sln
1000 mL sln 1 L sln
5 g Glc 100 mL sln
100
5 g Glu 100 mL sln
100 mL sln 5 g Glu
or
50
as Conversion Factor

• How many milliliters of alcohol are in an 8 oz
• glass of wine that is 11 v/v.

ml Alc
8 oz sln
1 qt sln 32 oz sln
946 ml sln 1 qt sln
11 ml Alc 100 ml sln
26
11 mL Alc 100 mL sln
100 mL sln 11 mL Alc
or
51
Concentration of solutions
How much solute is in a solution

• Percent

• Molarity M

mol solute M 1 L solution
52
Molarity
M
moles solute mol liters of solution
L
A 1 M glucose solution contains the same
molecules as 1 M ethanol.
special symbol which means mols
L
53
Molarity

• Calculate the molarity of a 2.0 L solution that
  contains 10 moles of NaOH.

M
moles solute mol liters of solution
L
MNaOH 10 mol NaOH 2.0 L
5 M NaOH
54
Molarity
Whats the molarity of a solution that has 18.23
g HCl in 2 liters?
1 mol HCl g HCl
0.25 M
18.23 g HCl 2 L sln
mol solute liters of sln
0.25
36.46
FW of HCl 1 H x 1.008 1 Cl x
35.45 36.46 g/mol
55
Solution preparation

• Solutions are typically prepared in 2 ways
• mixing the proper amount of solute and
  solvent.
• dilution of a concentrated solution.

56
Making a solution
Prepare 100 ml of a 0.5 M solution of sodium
chloride.

• How many gs of NaCl do you need to weigh out?

100 ml sln
1 L sln 1000 ml sln
0.5 mol NaCl 1 L sln
58.44 g NaCl 1 mol NaCl
grams NaCl
2.922
0.5 mol NaCl 1 L sln
1 L sln 0.5 mol NaCl
or
57
Making a solution
Prepare 100 ml of a 0.5 M solution of sodium
chloride.

• To make the solution

Weigh out 2.922 grams NaCl and transfer to a
volumetric flask.
Fill flask about 1/3 of the way with water and
gently swirl until the salt dissolves.
Dilute exactly to the mark, cap and mix.
58
Dilution
moles in soln 1 moles in soln 2
C1V1 C2V2
59
Dilution

• Once you have a solution, it can be diluted by
  adding more solvent. This is also important for
  materials only available as solutions
• M1V1 M2V2
• 1 initial
• 2 final
• Any volume or concentration unit can be used as
  long as you use the same units on both sides of
  the equation.

moles 1
moles 2
moles/liter x liters
moles/liter x liters
60
Dilution
C1V1 C2V2
What is the concentration of a solution produced
by diluting 100.0 ml of 1.5 M NaOH to 2.000
liters?

• C1 1.5 M C2 ?
• V1 100.0 ml V2 2000 ml

C2 C1V1 V2
C2 (1.5 M) (100.0 ml) 0.075 M (2000.
ml)
61
Colloids Suspensions

• Colloid Homogeneous mix
• But not a solution.

Particles larger (10-7 to 10-5 cm) than in a sln
(lt10-7 cm). But still dont settle out.
Suspension Heterogeneous mix
Large particles may settle out can be filtered.
62
Colloids

• Homogeneous mixtures of two or more substances
  which are not solutions.
• Dispersing medium - The substance in a colloid
  found in the greater extent.
• Dispersed phase - The substance found
• in the lesser extent.

• In colloidal suspensions, the particles are much
  larger than the solutes in a solution.
• For solutions, ions and molecules have a size of
  about 10-7 cm.
• In colloids, the particles larger, with sizes
  from 10-7 to 10-5 cm.
• The colloidal particles are still too small to
  settle out of solution due to gravity.

63
Colloids
Gaseous Medium Fog, Smoke
Liquid Medium
Cool whip, milk, paint,blood
Solid Medium Styrofoam Jelly,Opals
Pearls, Concrete
64
Types of colloids

• Dispersing Dispersed
• medium phase Name Example
• Gas Liquid Aerosol Fog
• Gas Solid Smoke
• Liquid Gas Foam Whipped cream
• Liquid Liquid Emulsion Milk, mayo
• Liquid Solid Sol Paint, ink
• Solid Gas Solid foam Marshmallow
• Solid Liquid Butter
• Solid Solid Pearls, opals

65
Tyndal effect

• Unlike solutions, colloidal suspensions exhibit
  light scattering.

1. purple gold sol 2. copper sulfate
solution 3. iron(III) hydroxide colloid
1 2 3
66
Osmosis
Semipermeable membrane
Concentrated Sln
Dilute Sln
Solvent small particles move
Solvent Tries to dilute the Concentrated sln
67
Osmosis
Apply P To return To original level
Hydrostatic P On membrane
68
Osmotic pressure (p)
P required to stop osmosis.
Remember Ideal Gas Eqn PVnRT
n R T V
P
Modified form
p
nMR T
Gas Constant
Mols of particles mol
69
Osmotic pressure (p)
p
nMRT
Mols of particles mol
mol L
L atm Mol K
K
p
MR T
Mols of particles Liter Sln
osmolarity (osmol)
70
Solution Types

• Isotonic
• Concentration is same on both sides.
• Red blood cell plasma

• Hypertonic
• Concentration greater outside
• crenation - water leaves cell

• Hypotonic
• Concentration greater inside
• hemolysis - cell swells ruptures

71
Hypotonic
Hypertonic
Isotonic
72
Osmosis and IV solutions
Isotonic Normal Saline (NS) 0.9 NaCl 5
Glucose Sln Used to replace body fluids
Hypertonic Used to draw water from tissue To
reduce swelling Gargling with salt H2O, Sitz
baths with epsom salts
Hypotonic Used to rehydrate tissue
73
Dialysis
Membrane w/ bigger holes than osmosis
Concentrated Sln
Dilute Sln
The process where solvent and other small
molecules can pass through a membrane.
Solvent small particles move
74
Dialysis

• The process where solvent and other small
  molecules can pass through a membrane.
• Similar to osmosis but the holes in the
  membrane are larger. As a result, even hydrated
  ions can pass through.
• The method relies on
• diffusion
• osmosis
• ultrafiltration

75
Dialysis

• By passing large amounts of a pure solvent past
  the membrane, we can flush out all but the
  largest components.

pure water in
water, ions and small molecule out
76
Medical applicationof dialysis

• This process is used to treat patients who
  suffer from acute and chronic renal disease.
• There are over 90,000 people currently
  undergoing this treatment in the U.S.
• The process does not replace normal renal
  function. It cant make the normal homeostatic
  adjustments of a normal kidney.

77

• Dialysis of patients is accomplished using one
  of two methods.
• Hemodialysis
• Arterial blood is passed to the dialyzer
• for purification. It is then returned to the
  body using a vein.
• Peritoneal dialysis
• The cycling of sterile dialysis fluid in and
  out of the peritoneal cavity.

78
Remember stoichiometry
Remember earlier stoichiometry problems. For
Example NaOH HCl ? NaCl HOH
How many moles of HCl are needed to react with
200 g NaOH?
1 mol HCl 1 mol NaOH
200g NaOH 1
1 mol NaOH 40g NaOH
5 mol HCl
79
Now Solution Stoichiometry
NaOH HCl ? NaCl HOH
How many L of 0.100 M HCl are needed to react
with 250 ml of 2.5 M NaOH?
250mL NaOH sln 1
2.5 mol NaOH 1 L NaOH sln
1 L NaOH sln 1000 mL NaOH sln
0.625 mol NaOH
1 L HCl 0.100 mol HCl
0.625 mol NaOH 1
1 mol HCl 1 mol NaOH
6.25 L of 0.100 M HCl sln
80
Colligative properties

• Bulk properties that change when you add a
  solute to make a solution.
• Based on how much you add but not what the solute
  is.
• Effect of ionic materials is based on number of
  ions produced.
• Colligative properties
• vapor pressure lowering
• freezing point depression
• boiling point elevation
• osmotic pressure

81
Vapor pressure

• All colligative properties are based on
• Raoults Law
• when a solute is added to a solvent, the
  pressure of the solution is due to the
  partial pressure of the solvent.
• Psolution Xsolvent Psolvent
• Of course, the solute cant be more volatile
  than the solvent you use.

82
Vapor pressure
Equal volumes
Higher volume
Water will end up in the salt solution because
its vapor pressure is lower than the pure water.
83
Boiling point elevation

• When you add a solute to a solvent, the boiling
  point will go up.
• BP elevation Kb x molality
• Dt n x Kb x m
• The more you add, the higher it goes.
• It will only work until you reach saturation.
• Examples Cooking pasta
• Antifreeze

84
Ionic vs. covalentsubstances

• Ionic substances have a greater effect per mole
  than covalent.
• 1 mole / kg of water for glucose 1 molal
• 1 mole / kg of water for NaCl 2 molal ions
• 1 mole / kg of water for CaCl2 3 molal ions
• Effects are based on the number of particles!
• This is the n we referred to earlier.

85
Liquid water Held by Hydrogen bonds
86
Freezing point depression

• When you add a solute to a solvent, the freezing
  point goes down.
• FP depression Kf x molality
• Dt n x Kf x m
• (where n is particles per formula.)
• The more you add, the lower it gets.
• This will only work until you reach saturation.
• Examples Salting roads in winter
• Making ice cream
• How does this happen???

mol kg
87
Frozen H2O slow moving molecules form hexagonal
rings resulting in crystals.

Solute particles interfere, causing the water
molecules to slow down even more. This reduces
the temperature.