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Solutions and Colloids. Homogeneous (or nearly homogeneous) Mixtures. Solutions. Homogeneous mixtures Solvent = dissolving medium often liquid; frequently water gas in air and other gas solutions rarely a solid Solute(s) = dissolved material(s) solids, liquids, and/or gases

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solutions and colloids

Solutions and Colloids

Homogeneous (or nearly homogeneous) Mixtures

solutions
Solutions
  • Homogeneous mixtures
  • Solvent = dissolving medium
    • often liquid; frequently water
    • gas in air and other gas solutions
    • rarely a solid
  • Solute(s) = dissolved material(s)
    • solids, liquids, and/or gases
    • often more than one solute
water as solvent
Water as Solvent
  • Form aqueous solutions
  • Many biological fluids are solutions or have solution components
  • One of best solvents for dissolving ionic substances
  • Poor solvent for non-polar covalent substances.
water

-

O

H

H

+

-

O

H

-

H

O

H

+

+

-

H

O

H

-

H

O

+

H

H

Water

“H-bonding” binds water molecules tightly.

water5
Water
  • Water is one of best solvents for ionic material (electrolytes)
  • Water’s polar molecular structure interacts strongly with charged ions
  • Water---Ion attractions replace ion---ion and water---water attractions with little net energy change
water6
Water

Crystal’s +/- attractions cause lattice energy, which must be overcome to break up crystal.

Na+

Cl-

water7
Water

Na+

Cl-

water8
Water

“Void” weakens crystal and makes it more likely to break up in vicinity.

Several more H2O molecules may associate

Na+

Cl-

water9
Water

Na+

Cl-

water10
Water

Na+

Cl-

water11
Water

+/- forces release energy

Note:Positive ions associate with negative ends of waters, and negative ions associate with positive ends of waters.

Na+

Cl-

water12
Water
  • In similar fashion, the entire crystal dissolves
    • positive ions link to oxygen of water
    • negative ions link to hydrogen of water
    • process call hydration
  • Hydration releases energy
  • Hydration energy compensates for lattice energy.
water14
Water

An exothermic dissolving process.

Hydration energy is greater than lattice energy.

water16
Water

An endothermic dissolving process.

Lattice energy is greater than hydration energy.

water17
Water
  • Exothermic processes release energy
    • Temperature of surroundings increase.
    • Hydration energy grater than lattice energy.
  • Endothermic processes absorb energy.
    • Temperature of surroundings decrease.
    • Lattice energy greater than hydration energy.
solution concentrations
Solution Concentrations
  • Dilute
    • Small amount of solute for given solvent
  • Concentrated
    • Large amount of solute for given solvent
  • Saturated
    • Maximum amount of solute for given solvent
  • But these terms are qualitative, not quantitative, and are open to interpretation.
solution concentrations20

.

Solution Concentrations

Dilute or Concentrated???

solution concentrations21

.

.

Solution Concentrations

Dilute or Concentrated???

solution concentrations22
Solution Concentrations
  • It depends, of course, on one’s point of view.
    • It’s only a teaspoon in 20 gallons.
    • Dilute??
    • But this concentration is far beyond the lethal dose for the fish.
    • Concentrated???
solution concentrations23

grams

Concentration =

mL

Solution Concentrations

Expressed as a ratio of the amount of solute to the total amount of solution:

Amount of solute

Total amount of solution

(%, w/v)

solution concentrations24

mass (grams)

Concentration =

mass unit (grams)

Solution Concentrations

Expressed as a ratio of the amount of solute to the total amount of solution:

Amount of solute

Total amount of solution

(%, w/w)

solution concentrations25

dL

Concentration =

mg

Solution Concentrations

Expressed as a ratio of the amount of solute to the total amount of solution:

Amount of solute

Total amount of solution

( mg %)

solution concentrations26

Concentration =

moles

Liters

Solution Concentrations

Expressed as a ratio of the amount of solute to the total amount of solution:

Amount of solute

Total amount of solution

( molarity, M)

solution concentrations27

Grams of solute

%, w/v=

mL of solution

Solution Concentrations

% Concentration has multiplier of 100 to place ratio on “parts per 100” basis:

X 100

solution concentrations28

Grams of solute

‰=

mL of solution

Solution Concentrations

‰ Concentration has multiplier of 1000 to place ratio on “parts per 1000 total” basis:

X 1000

solution concentrations29

Grams of solute

ppm =

mL of solution

Solution Concentrations

ppm concentration has multiplier of 106 to place ratio on “parts per million total” basis:

X 106

solution concentrations30

Grams of solute

%, w/v=

mL of solution

% =

X 100

Solution Concentrations

Practice situation:

4.75 grams of NaCl is dissolved in sufficient water to make 750 mL of solution.

What is the % (w/v) concentration of this solution?

4.75 g

X 100

= 0.633 %

750 mL

The g/mL units are understood but not included.

solution concentrations31

0.633%

NaCl

Solution Concentrations

4.75 grams of NaCl is dissolved in sufficient water to make 750 mL of solution.

What is the % (w/v) concentration of this solution?

The concentration is 0.633 % (w/v).

750 mL

solution concentrations32

Grams of solute

%, w/v=

mL of solution

% =

X 100

Solution Concentrations

Another:

12.5 grams of H2SO4 is dissolved in sufficient water to make 0.500 liters of solution.

What is the % (w/v) concentration of this solution?

Solution volume units must be converted from liters to mL before doing calculations: 0.500 L = 500 mL.

12.5 g

X 100

= 2.50 %

500 mL

The g/mL units are understood but not included.

solution concentrations33
Solution Concentrations
  • Once known, the solution concentration works as a conversion factor.
    • Establishes the “relationship” between amount of solute and volume of solution.
    • For % (w/v) concentrations, conversion factors derive from this relationship:

“%-Value” grams of solute = 100 mL solution

solution concentrations34

100 mL solution

0.85 g NaCl

0.85 g NaCl

100 mL solution

Solution Concentrations

Once known, the solution concentration work as a conversion factor.

Examples (all are wt/vol percents):

0.85 % NaCl

means…

0.85 g NaCl = 100 mL solution

and the conversion factors are…

or

solution concentrations35

0.85%

NaCl

Solution Concentrations

Using the concentration as a conversion factor:

Examples (all are wt/vol percents):

What mass of NaCl is present in 2000 mL of 0.85% NaCl solution?

How much dissolved NaCl is in this 2000 mL of saline solution?

solution concentrations36

0.85 g NaCl

100 mL solution

Solution Concentrations

Using the concentration as a conversion factor:

Examples (all are wt/vol percents):

What mass of NaCl is present in 2000 mL of 0.85% NaCl solution?

2000 mL soln

X

17.0 g NaCl

=

solution concentrations37

0.85%

NaCl

Solution Concentrations

Using the concentration as a conversion factor:

Examples (all are wt/vol percents):

What mass of NaCl is present in 2000 mL of 0.85% NaCl solution?

17.0 grams of dissolved NaCl is present in 2000 mL of this solution

solution concentrations38

What volume will contain 2.50 grams of dissolved NaCl?

0.85%

NaCl

Solution Concentrations

Using the concentration as a conversion factor:

Examples (all are wt/vol percents):

What volume of 0.85% NaCl solution should contain 2.50 grams of dissolved NaCl?

solution concentrations39

100 mL solution

0.85 g NaCl

Solution Concentrations

Using the concentration as a conversion factor:

Examples (all are wt/vol percents):

What volume of 0.85% NaCl solution should contain 2.50 grams of dissolved NaCl?

2.50 g NaCl

X

294 mL soln

=

solution concentrations40

294 mL of this solution contains 2.50 grams of dissolved NaCl.

0.85%

NaCl

Solution Concentrations

Using the concentration as a conversion factor:

Examples (all are wt/vol percents):

What volume of 0.85% NaCl solution should contain 2.50 grams of dissolved NaCl?

solution concentrations41
Solution Concentrations

Three types of calculations dealing with concentrations:

  • Given the amount of solute and total solution, determine the concentration.
  • Given the concentration and amount of solution, find the amount of solute.
  • Given the concentration and the amount of solute, determine the amount of solution.
solution concentrations42

Amount of solute

Concentration =

Total amount of solution

Solution Concentrations

Three types of calculations dealing with concentrations:

2

3

1

solution concentrations43

Amount of solute

Concentration =

Total amount of solution

Solution Concentrations

Given any two, be able to calculate the third:

2

3

1

solution concentrations44

Moles of solute

Liters of solution

M =

Solution Concentrations

Molarity

4.75 grams of NaCl is dissolved in sufficient water to make 750 mL of solution.

What is the molarity of NaCl in this solution?

We previously determined this solution to be 0.633%; what is its molarity?

solution concentrations45

Moles of solute

Liters of solution

M =

Solution Concentrations

Molarity

The 4.75 grams of NaCl will need to be converted to moles before the calulations are done.

Similarly, to make units match, the 750 mL will be converted to liters.

solution concentrations46

Moles of solute

Liters of solution

M =

1 Liter

1 mole NaCl

58.5 g NaCl

1000 mL

Solution Concentrations

Molarity

4.75 grams of NaCl is dissolved in sufficient water to make 750 mL of solution. M = ?

4.75 g NaCl

X

0.0812 mole NaCl

=

750 mL

X

0.750 L

=

solution concentrations47

Moles of solute

0.0812 moles NaCl

Liters of solution

0.750 Liters of solution

M =

M =

0.0812 mole NaCl

0.750 L

Solution Concentrations

4.75 grams of NaCl is dissolved in sufficient water to make 750 mL of solution. M = ?

= 0.108 M NaCl

= 0.108 moles NaCl/L

solution concentrations48

0.633%

0.108 M

NaCl

Solution Concentrations

4.75 grams of NaCl is dissolved in sufficient water to make 750 mL of solution.

What is the % (w/v) concentration of this solution and what is its molarity?

The concentration is 0.633 % (w/v)

and…

is 0.108 M

750 mL

solution concentrations49

Amount of solute

Concentration =

Total amount of solution

Solution Concentrations

Given any two, be able to calculate the third:

2

3

1

solution concentrations50

0.225M

NaCl

Solution Concentrations

Using the concentration as a conversion factor:

Examples (all are wt/vol percents):

How many moles of NaCl is present in 2000 mL of 0.225-M NaCl solution?

How much dissolved NaCl is in this 2000 mL of saline solution?

solution concentrations51

1 L

1000 mL

0.225 moles NaCl

0.225 moles NaCl

1 L solution

1000 mL solution

Solution Concentrations

Using the concentration as a conversion factor:

How many moles of NaCl is present in 2000 mL of 0.225-M NaCl solution?

x

x

2000 mL soln

=

0.450 moles

Or…

x

2000 mL soln

=

0.450 moles NaCl

solution concentrations52

1000 mL

1 L

1 L

0.225 Moles

1000 mL solution

0.225 moles NaCl

Solution Concentrations

Using the concentration as a conversion factor:

What volume of 0.225-M NaCl solution will contain 0.0175 moles of dissolved NaCl?

x

x

=

77.8 mL

0.0175 moles

Or…

x

77.8 mL soln

=

0.0175 moles NaCl

solution stoichiometry
Solution Stoichiometry
  • Just as grams of a pure substance and its FW determine moles of the substance, so do volulme and molarity of a substance in its solution.
  • As for “pure substance” stoichiometry, solution stoichiometry usually involves a three-step approach:
solution stoichiometry54
Solution Stoichiometry

Consider reaction of 0.200-M HCl with sodium carbonate:

2HCl + Na2CO3 2NaCl + CO2 + H2O

? g

25.0 mL

Use volume and

HCl molarity

Use moles and

FW of Na2CO3

? moles

? moles

Use Equation

Coefficients

How many grams of Na2CO3 will react with 25.0 mL of 0.200-M HCl solution?

solution stoichiometry55

106 g Na2CO3

1 mole Na2CO3

0.200 mole HCl

1 mole Na2CO3

2 mole HCl

1000 mL HCl

Solution Stoichiometry

Consider reaction of 0.200-M HCl with sodium carbonate:

2HCl + Na2CO3 2NaCl + CO2 + H2O

? g

25.0 mL

Use volume and

HCl molarity

Use moles and

FW of Na2CO3

? moles

? moles

Use Equation

Coefficients

x

x

25.0 mL HCl

x

= 0.265 grams Na2CO3

solution stoichiometry56
Solution Stoichiometry

Consider reaction of 0.200-M HCl with sodium carbonate:

2HCl + Na2CO3 2NaCl + CO2 + H2O

? mL

5.00 g

Use moles and

HCl molarity

Use grams and FW

? moles

? moles

Use Equation

Coefficients

What volume of 0.200-M HCl solution is required for reaction with 5.00 grams of Na2CO3?

solution stoichiometry57

1000 mL HCl

2 mole HCl

1 mole Na2CO3

0.200 mole HCl

1 mole Na2CO3

106 g Na2CO3

Solution Stoichiometry

Consider reaction of 0.200-M HCl with sodium carbonate:

2HCl + Na2CO3 2NaCl + CO2 + H2O

? mL

5.00 g

Use moles and

HCl molarity

Use grams and FW

? moles

? moles

Use Equation

Coefficients

x

x

5.00g Na2CO3

x

= 472 mL HCl solution

solutions vs colloids
Solutions vs Colloids
  • Solution
    • Solute particle are of ionic or molecular size (a few nm across)
    • Transparent to ordinary light
    • Stable unless solvent evaporated
  • Colloids
    • Solute (called “dispersed phase”) typically 1000 nm or more per particle
    • Giant molecules (or “clumps” of smaller ones)
    • Not totally transparent – Tyndall Effect
    • Dispersed phase may separate out (similar to separation of mayonnaise).
solutions vs colloids59
Solutions vs Colloids

The Tyndall Effect

True

Solution

Colloidal

Mixture

solutions vs colloids60
Solutions vs Colloids

The Tyndall Effect

True

Solution

Colloidal

Mixture

slide61

Transmembrane Diffusion

Solution

(H2O +

Solutes)

Pure

H2O

Semipermeable membrane

Only water passes through osmotic membranes and faster from the side on which water is more concentrated.

slide62

Transmembrane Diffusion

Solution

(H2O +

Solutes)

Pure

H2O

Semipermeable membrane

Diffusion rates tend to equalize as flow continues.

slide64

Osmotic Pressure

If applied pressure is too low, H2O flows into the region of higher solute concentration...

“Down the concentration gradient” for H2O.

P

P

Membrane

Pure H2O

H2O +

Solutes

slide65

Osmotic Pressure

P

If applied pressure is too high, H2O flows into the region of lower solute concentration...

Against the natural concentration gradient for H2O.

--Reverse Osmosis

P

Membrane

Pure H2O

H2O +

Solutes

slide66

P

Osmotic Pressure

P

Minimum pressure required to maintain equal flow rates (to prevent infusion of H2O).

Proportional to solute concentration differences across membrane.

Membrane

Pure H2O

H2O +

Solutes

solutions vs colloids67
Solutions vs Colloids
  • Solution
    • Solute particles are of ionic or molecular size
    • Transparent to ordinary light
    • Stable unless solvent evaporated
    • May pass through dialytic, but not true osmotic, membranes
  • Colloids
    • Typically 1000 nm or more per particle
    • Not totally transparent – Tyndall Effect
    • May separate out
    • Particles too large to pass through most membranes
slide68

H2O

NaCl

Transmembrane Diffusion

Mixture

(H2O,

Na+Cl-,

protein)

NaCl more concen-trated here

Pure

H2O

H2O more concentrated here

Dialytic membrane

Water and solutes pass down concentration gradient through dialytic membrane. Colloids do not cross membrane.

solution concentrations69

Concentration =

Osmoles (total moles)

Liters

Solution Concentrations

Expressed as a ratio of the amount of solute to the total amount of solution:

Amount of solute

Total amount of solution

( Osmolarity, osM)

For certain solutes, osM will equal M.

osmolarity
Osmolarity
  • Calculating
    • Total of molarities of all types of solute particles in the solution.
    • For ionic solutes, the ions are separated; and each ion has a separate molarity to be totaled.
    • Molecular solutes have same molarity and osmolarity, but each different solute needs to be included.
  • Impact
    • Osmolarity determines osmotic pressure
    • Useful in determining net direction of H2O flow across membranes.
osmolarity71
Osmolarity

Osmolarity

Solute, M

0. 25-M C6H12O6 (molecular)

0. 25-osM

0. 25-M NaCl (ionic)

0. 50-osM

(0.25-M Na+ + 0.25-M Cl-)

0. 10-M CaBr2 (ionic)

0. 30-osM

(0.10-M Ca+ + 0.20-M Br-)

0. 25-osM

(0.10-M Fe3+ + 0.15-M SO42-)

0. 05-M Fe2(SO4)3 (ionic)

slide72

H2O

Ca2+

Cl-

C6H12O6

0.2 osM

0.2 osM

0.6 osM

0.3 osM

0.2 osM

0.1 osM

Transmembrane Diffusion

Dialytic membrane

0.6 osM

+ 1% colloid

1.0 osM

+ 2% colloid

A

B

0.1-M NaCl

0.1-M CaCl2

0.1-M C6H12O6

1% starch

0.1-M NaCl

0.2-M CaCl2

0.2-M C6H12O6

2% starch

slide73

H2O

Cl-

C6H12O6

Ca2+

Hypotonic

Hypertonic

Transmembrane Diffusion

Dialytic membrane

0.6 osM

+ 1% colloid

1.0 osM

+ 2% colloid

A

B

0.1-M NaCl

0.1-M CaCl2

0.1-M C6H12O6

1% starch

0.1-M NaCl

0.2-M CaCl2

0.2-M C6H12O6

2% starch

Water flows into hypertonic fluid (where water is less concentrated).

slide74

“Head pressure” --High

“Head pressure” --Low

Arterial End

Venous End

Wastes

Nutrients

Head pressure of heart “pushes” nutrients and water into cell (PBLOOD> POSMOTIC).

Hypertonic blood “draws” wastes into blood (POSMOTIC>PBLOOD) .

Transmembrane Diffusion

Tissue Cell

solution concentrations75

0.633%

NaCl

Solution Concentrations

4.75 grams of NaCl is dissolved in sufficient water to make 750 mL of solution.

What is the % (w/v) concentration of this solution?

The concentration is 0.633 % (w/v).

750 mL