Solutions and Colloids Homogeneous (or nearly homogeneous) Mixtures.

Solutions and ColloidsSolutions and Colloids

Homogeneous (or nearly Homogeneous (or nearly homogeneous) Mixtureshomogeneous) Mixtures

SolutionsSolutions

Homogeneous mixturesHomogeneous mixtures SolventSolvent = dissolving medium = dissolving medium

– often liquid; frequently wateroften liquid; frequently water– gas in air and other gas solutionsgas in air and other gas solutions– rarely a solidrarely a solid

Solute(s) Solute(s) = dissolved material(s)= dissolved material(s)– solids, liquids, and/or gasessolids, liquids, and/or gases– often more than one soluteoften more than one solute

Water as SolventWater as Solvent

Form Form aqueous solutionsaqueous solutions Many biological fluids are solutions Many biological fluids are solutions

or have solution componentsor have solution components One of best solvents for dissolving One of best solvents for dissolving

ionic substancesionic substances Poor solvent for non-polar covalent Poor solvent for non-polar covalent

substances.substances.

WaterWater

HHHH

OO--

++OO

HH

HH

++--

OO

HHHH

++

--

OOHH

HH

--

OOHHHH

++

--

“H-bonding” binds water molecules tightly.

WaterWater

Water is one of best solvents for ionic Water is one of best solvents for ionic material (electrolytes)material (electrolytes)

Water’s polar molecular structure Water’s polar molecular structure interacts strongly with charged ionsinteracts strongly with charged ions

WaterWater------IonIon attractions replace attractions replace ion---ion and and waterwater------waterwater attractions attractions with little net energy changewith little net energy change

WaterWater

Na+ Cl-

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

WaterWater

Na+ Cl-

WaterWater

Na+ Cl-

Several more H2O molecules may associate

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

WaterWater

Na+ Cl-

WaterWater

Na+ Cl-

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

+/- forces release energy

WaterWater

In similar fashion, the entire crystal In similar fashion, the entire crystal dissolvesdissolves– positive ions link to oxygen of waterpositive ions link to oxygen of water– negative ions link to hydrogen of waternegative ions link to hydrogen of water– process call process call hydrationhydration

Hydration releases energyHydration releases energy Hydration energyHydration energy compensates for compensates for

lattice energy. lattice energy.

WaterWater

WaterWater

An exothermic dissolving process.Hydration energy is greater than lattice energy.

WaterWater

WaterWater

An endothermic dissolving process.Lattice energy is greater than hydration energy.

WaterWater

Exothermic Exothermic processes release energyprocesses release energy– Temperature of surroundings Temperature of surroundings increase.increase.– Hydration Hydration energy grater than lattice energy grater than lattice

energy.energy. Endothermic Endothermic processes absorb energy.processes absorb energy.

– Temperature of surroundings Temperature of surroundings decreasedecrease..– Lattice Lattice energy greater than hydration energy greater than hydration

energy.energy.

Solution ConcentrationsSolution Concentrations

DiluteDilute– Small amount of solute for given solventSmall amount of solute for given solvent

ConcentratedConcentrated– Large amount of solute for given solventLarge amount of solute for given solvent

SaturatedSaturated– Maximum amount of solute for given solventMaximum amount of solute for given solvent

But these terms are qualitative, not But these terms are qualitative, not quantitative, and are open to quantitative, and are open to interpretation.interpretation.


.

20 gal.


.

Dilute or Concentrated???


Dilute or Concentrated???

.

.


It depends, of course, on one’s point of It depends, of course, on one’s point of view.view.– It’s only a teaspoon in 20 gallons.It’s only a teaspoon in 20 gallons.– Dilute??Dilute??– But this concentration is far beyond the But this concentration is far beyond the

lethal dose for the fish.lethal dose for the fish.– Concentrated???Concentrated???


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

Concentration =Amount of solute

Total amount of solution

grams

mL

(%, w/v)





mass (grams)

mass unit (grams)

(%, w/w)





dL

( mg %)

mg





moles

Liters

( molarity, M)


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

Grams of solute

mL of solution%, w/v = X 100


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

Grams of solute

mL of solution‰ = X 1000


ppm concentration has multiplier of 10ppm concentration has multiplier of 1066 to to place ratio on “parts per million total” basis:place ratio on “parts per million total” basis:

Grams of solute

mL of solutionppm = X 106

Solution ConcentrationsSolution ConcentrationsPractice situation: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?

Grams of solute


% = 4.75 g750 mL

X 100 = 0.633 %

The g/mL units are understood but not included.


0.633%NaCl

The concentration The concentration is 0.633 % (is 0.633 % (w/vw/v).).


750 mL

Solution ConcentrationsSolution ConcentrationsAnother: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?

Grams of solute


% = 12.5 g500 mL

X 100 = 2.50 %

The g/mL units are understood but not included.

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


Once known, the solution Once known, the solution concentration works as a conversion concentration works as a conversion factor.factor.– Establishes the “relationship” between Establishes the “relationship” between

amount of solute and volume of solution.amount of solute and volume of solution.– For % (For % (w/vw/v) concentrations, conversion ) concentrations, conversion

factors derive from this relationship:factors derive from this relationship:

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

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

Examples (all are Examples (all are wt/volwt/vol percents): percents):

0.85 %0.85 % NaCl NaClmeans…means…0.85 g0.85 g NaCl = NaCl = 100 mL100 mL solution solutionand the conversion factors are…and the conversion factors are…

0.85 g0.85 g NaCl NaCl

100 mL100 mL solution solutionoror

0.85 g0.85 g NaCl NaCl

100 mL100 mL solution solution

Solution ConcentrationsSolution ConcentrationsUsing the concentration as a conversion Using the concentration as a conversion factor:factor:


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

0.85%NaCl

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



0.85 g NaCl0.85 g NaCl

100 mL solution100 mL solution


2000 mL soln2000 mL soln XX == 17.0 g NaCl17.0 g NaCl




0.85%NaCl

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



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

0.85%NaCl

What volume will contain What volume will contain 2.50 grams of dissolved 2.50 grams of dissolved NaCl?NaCl?




2.50 g NaCl2.50 g NaCl XX == 294 mL soln294 mL soln0.85 g0.85 g NaCl NaCl

100 mL100 mL solution solution




0.85%NaCl

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


Given the Given the amount of soluteamount of solute and and total total solutionsolution, determine the , determine the concentrationconcentration..

Given the Given the concentration concentration and and amount of amount of solutionsolution, find the , find the amount of soluteamount of solute..

Given the Given the concentrationconcentration and the and the amount amount of soluteof solute, determine the , determine the amount of amount of solutionsolution..

Three types of calculations dealing Three types of calculations dealing with concentrations:with concentrations:


Three types of calculations dealing Three types of calculations dealing with concentrations:with concentrations:

Concentration =Concentration =Amount of soluteAmount of solute

Total amount of solutionTotal amount of solution

13

2


Given Given any twoany two, be able to calculate , be able to calculate the third:the third:



13

2


MolarityMolarity

M =M =Moles of soluteMoles of solute

Liters of solutionLiters of solution

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


MolarityMolarity



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

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

Solution ConcentrationsSolution ConcentrationsMolarityMolarity



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

4.75 g NaCl4.75 g NaCl XX == 0.0812 mole NaCl0.0812 mole NaCl58.5 g58.5 g NaCl NaCl

1 mole 1 mole NaClNaCl

750 mL750 mL XX == 0.750 L0.750 L1000 mL1000 mL

1 Liter1 Liter

Solution ConcentrationsSolution Concentrations4.75 grams of NaCl is dissolved in sufficient water to make 750 mL of solution. M = ?

0.0812 mole NaCl0.0812 mole NaCl

0.750 L0.750 L



= 0.108 = 0.108 M M NaCl NaCl= 0.108 moles NaCl/L= 0.108 moles NaCl/L

M =M =0.0812 moles NaCl0.0812 moles NaCl

0.750 Liters of solution0.750 Liters of solution


0.633%0.108 M

NaCl

The concentration The concentration is 0.633 is 0.633 %% ( (w/vw/v)) andand……is 0.108 is 0.108 MM

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?

750 mL


Given Given any twoany two, be able to calculate , be able to calculate the third:the third:



13

2



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

0.225MNaCl

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


0.225 moles NaCl0.225 moles NaCl

1 L solution1 L solution

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

2000 mL soln2000 mL soln xx == 0.450 moles0.450 molesxx 1 L1 L1000 mL1000 mL

0.225 moles NaCl0.225 moles NaCl

1000 mL solution1000 mL solution2000 mL soln2000 mL soln == 0.450 moles NaCl0.450 moles NaClxx

Or…Or…


1000 mL1000 mL

1 L1 L

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

0.0175 moles0.0175 moles xx == 77.8 mL77.8 mLxx 1 L1 L0.225 Moles0.225 Moles

1000 mL solution1000 mL solution

0.225 moles NaCl0.225 moles NaCl0.0175 moles NaCl0.0175 moles NaCl == 77.8 mL soln77.8 mL solnxx

Or…Or…

Solution StoichiometrySolution Stoichiometry

Just as grams of a pure substance and Just as grams of a pure substance and its FW determine its FW determine molesmoles of the of the substance, so do volulme and substance, so do volulme and molarity of a substance in its solution.molarity of a substance in its solution.

As for “pure substance” As for “pure substance” stoichiometry, solution stoichiometry stoichiometry, solution stoichiometry usually involves a three-step usually involves a three-step approach:approach:


2HCl + Na2HCl + Na22COCO33 2NaCl + CO 2NaCl + CO22 + H + H22OO

Consider reaction of 0.200-Consider reaction of 0.200-MM HCl with sodium carbonate: HCl with sodium carbonate:

How many grams of NaHow many grams of Na22COCO33 will react with 25.0 will react with 25.0

mL of 0.200-mL of 0.200-MM HCl solution? HCl solution?

25.0 mL25.0 mL

? moles? moles ? moles? moles

? g? g

Use volume andUse volume andHCl molarityHCl molarity

Use EquationUse EquationCoefficientsCoefficients

Use moles andUse moles andFW of NaFW of Na22COCO33


2HCl + Na2HCl + Na22COCO33 2NaCl + CO 2NaCl + CO22 + H + H22OO

Consider reaction of 0.200-Consider reaction of 0.200-MM HCl with sodium carbonate: HCl with sodium carbonate:

25.0 mL25.0 mL

? ? molesmoles ? moles? moles

? g? g

Use volume andUse volume andHCl molarityHCl molarity


Use moles andUse moles andFW of NaFW of Na22COCO33

25.0 mL HCl25.0 mL HCl xx1000 mL HCl1000 mL HCl

0.200 mole HCl0.200 mole HCl xx2 mole HCl2 mole HCl

1 mole Na1 mole Na22COCO33 xx106 g Na106 g Na22COCO33

1 mole Na1 mole Na22COCO33

= = 0.265 grams Na0.265 grams Na22COCO33


2HCl + Na2HCl + Na22COCO33 2NaCl + CO 2NaCl + CO22 + H + H22OOConsider reaction of 0.200-Consider reaction of 0.200-M M HCl with sodium carbonate:HCl with sodium carbonate:

What volume of 0.200-What volume of 0.200-MM HCl solution is required HCl solution is required for reaction with 5.00 grams of Nafor reaction with 5.00 grams of Na22COCO33??

5.00 g5.00 g

? moles? moles? moles? moles

? mL? mL

Use grams and FWUse grams and FW


Use moles andUse moles andHCl molarityHCl molarity


2HCl + Na2HCl + Na22COCO33 2NaCl + CO 2NaCl + CO22 + H + H22OOConsider reaction of 0.200-Consider reaction of 0.200-M M HCl with sodium carbonate:HCl with sodium carbonate:

5.00 g5.00 g

? moles? moles? moles? moles

? mL? mL

Use grams and FWUse grams and FW


Use moles andUse moles andHCl molarityHCl molarity

5.00g Na5.00g Na22COCO33 xx106 g Na106 g Na22COCO33

1 mole Na1 mole Na22COCO33 xx1 mole Na1 mole Na22COCO33

2 mole HCl2 mole HClxx

= = 472 mL HCl solution472 mL HCl solution

0.200 mole HCl0.200 mole HCl1000 mL HCl1000 mL HCl

Solutions Solutions vs vs ColloidsColloids SolutionSolution

– Solute particle are of ionic or molecular Solute particle are of ionic or molecular size (a few nm across)size (a few nm across)

– Transparent to ordinary lightTransparent to ordinary light– Stable unless solvent evaporatedStable unless solvent evaporated

ColloidsColloids– Solute (called “dispersed phase”) Solute (called “dispersed phase”)

typically 1000 nm or more per particletypically 1000 nm or more per particle– Giant molecules (or “clumps” of smaller Giant molecules (or “clumps” of smaller

ones)ones)– Not totally transparent – Tyndall EffectNot totally transparent – Tyndall Effect– Dispersed phase may separate out Dispersed phase may separate out

(similar to separation of mayonnaise).(similar to separation of mayonnaise).

Solutions Solutions vs vs ColloidsColloids

ColloidalColloidalMixtureMixture

TrueTrueSolutionSolution

The Tyndall EffectThe Tyndall Effect

Semipermeable membraneSemipermeable membrane

PurePureHH22OO

SolutionSolution(H(H22O +O +

Solutes)Solutes)

Transmembrane DiffusionTransmembrane Diffusion

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

Semipermeable membraneSemipermeable membrane

PurePureHH22OO

SolutionSolution(H(H22O +O +

Solutes)Solutes)


Diffusion rates tend to equalize as flow continues.Diffusion rates tend to equalize as flow continues.

Pure Pure HH22OO

HH22O +O +

Solutes Solutes

Osmotic PressureOsmotic PressureIf applied If applied pressure is too pressure is too low, Hlow, H22O flows O flows

into the region into the region of higher of higher solute solute concentration...concentration...

““Down the Down the concentration concentration gradient” for gradient” for HH22O.O.

P

MembraneMembrane

P

Pure Pure HH22OO

HH22O +O +

Solutes Solutes

Osmotic PressureOsmotic PressureIf applied If applied pressure is too pressure is too high, Hhigh, H22O flows O flows

into the region into the region of lower of lower solute solute concentration...concentration...

Against the Against the natural natural concentration concentration gradient for gradient for HH22O.O.

--Reverse --Reverse OsmosisOsmosis

P

MembraneMembrane

P

Pure Pure HH22OO

HH22O +O +

Solutes Solutes

Osmotic PressureOsmotic PressureMinimum Minimum pressure pressure required to required to maintain equal maintain equal flow rates (to flow rates (to prevent infusion prevent infusion of Hof H22O).O).

Proportional to Proportional to solute solute concentration concentration differences differences across across membrane.membrane.

P

MembraneMembrane

P

Solutions Solutions vs vs ColloidsColloids SolutionSolution

– Solute particles are of ionic or molecular Solute particles are of ionic or molecular sizesize

– Transparent to ordinary lightTransparent to ordinary light– Stable unless solvent evaporatedStable unless solvent evaporated– May pass through dialytic, but not true May pass through dialytic, but not true

osmotic, membranesosmotic, membranes ColloidsColloids

– Typically 1000 nm or more per particleTypically 1000 nm or more per particle– Not totally transparent – Tyndall EffectNot totally transparent – Tyndall Effect– May separate outMay separate out– Particles too large to pass through Particles too large to pass through

most membranesmost membranes

Dialytic membraneDialytic membrane

PurePureHH22OO

MixtureMixture(H(H22O,O,

NaNa++ClCl--,,protein)protein)


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

HH22OO

NaClNaCl

HH22O O more more

concentrated concentrated herehere

NaCl NaCl more more concen-concen-trated trated herehere





Osmoles (total moles)

Liters

( Osmolarity, osM)

For certain solutes, For certain solutes, osMosM will equal will equal MM..

OsmolarityOsmolarity CalculatingCalculating

– Total of molarities of all types of solute Total of molarities of all types of solute particles in the solution.particles in the solution.

– For ionic solutes, the ions are separated; and For ionic solutes, the ions are separated; and each ion has a separate molarity to be totaled.each ion has a separate molarity to be totaled.

– Molecular solutes have same molarity and Molecular solutes have same molarity and osmolarity, but each different solute needs to osmolarity, but each different solute needs to be included.be included.

ImpactImpact– Osmolarity determines osmotic pressureOsmolarity determines osmotic pressure– Useful in determining net direction of HUseful in determining net direction of H22O flow O flow

across membranes.across membranes.

OsmolarityOsmolarity

Solute, Solute, MM OsmolarityOsmolarity

0. 25-0. 25-M M CC66HH1212OO66 (molecular) (molecular) 0. 25-os0. 25-osMM

0. 25-0. 25-M M NaCl (ionic)NaCl (ionic) 0. 50-os0. 50-osMM(0.25-(0.25-MM Na Na++ + 0.25- + 0.25-MM Cl Cl--))

0. 10-0. 10-M M CaBrCaBr22 (ionic) (ionic) 0. 30-os0. 30-osMM(0.10-(0.10-MM Ca Ca++ + 0.20- + 0.20-MM Br Br--))

0. 05-0. 05-M M FeFe22(SO(SO44))33 (ionic) (ionic) 0. 25-os0. 25-osMM(0.10-(0.10-MM Fe Fe3+3+ + 0.15- + 0.15-MM SO SO44

2-2-))

HH22OO



ClCl--

0.1-0.1-M M NaClNaCl0.1-0.1-MM CaCl CaCl22

0.1-0.1-MM C C66HH1212OO66

1% starch1% starch


0.2-0.2-MM C C66HH1212OO66

2% starch2% starch

AA BB

CC66HH1212OO66

CaCa2+2+

1.0 os1.0 osM M + 2% + 2% colloidcolloid

0.2 os0.2 osMM

0.6 os0.6 osMM

0.2 os0.2 osMM

0.2 os0.2 osMM

0.3 os0.3 osMM

0.1 os0.1 osMM


HH22OO



ClCl--


0.1-0.1-MM C C66HH1212OO66

1% starch1% starch


0.2-0.2-MM C C66HH1212OO66

2% starch2% starch

AA BB

CC66HH1212OO66

CaCa2+2+



HypoHypotonictonicHyperHypertonictonic

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


““Head Head pressure” --pressure” --HighHigh

““Head Head pressure” --pressure” --LowLow

Tissue CellTissue Cell

NutrientsNutrients

WastesWastes

Venous E

ndV

enous End

Arterial E

ndA

rterial End

Hypertonic blood “draws” Hypertonic blood “draws” wastes into blood wastes into blood (P(POSMOTICOSMOTIC>P>PBLOODBLOOD) .) .

Head pressure of heart Head pressure of heart “pushes” nutrients and “pushes” nutrients and water into cell (Pwater into cell (PBLOODBLOOD> >

PPOSMOTICOSMOTIC).).


0.633%NaCl

The concentration The concentration is 0.633 % (is 0.633 % (w/vw/v).).


750 mL

Solutions and Colloids Homogeneous (or nearly homogeneous) Mixtures.

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