Lecture 4:Solution & Properties of Solutions pdf - د. علاء محراث

Solution &

Properties of solutions

Dr.Alaa J.Mahrath

Medical Chemistry College of Medicine

LEARNING GOAL

• Identify a mixture as a solution

a colloid

, or

a suspension.

• Describe how the number of particles in a solution

affects the

osmotic pressure

of a solution .

i.e. The size and number of solute particles in

different types of mixtures play an important role in

determining the properties of that mixture.

• Electrolytes
• Isotonic , Hypotonic and Hypertonic .
• Dialysis .

AJM Bioorgchem UBCMCD

Read this Story about Solution

• When

Michelle

’s kidneys stopped functioning, she was

placed on

dialysis three times a week

. As she enters the

dialysis unit, her dialysis nurse,

Amanda

, asks Michelle

how she is feeling. Michelle indicates that she feels tired
today and has considerable swelling around her ankles.

• The dialysis nurse informs Michelle that her side effects

are due to her body’s inability to regulate the amount of
water in her cells.

• She explains that the amount of water is regulated by the

concentration of electrolytes in her body fluids and the
rate at which waste products are removed from her
body.

AJM Bioorgchem UBCMCD

Michelle and Amanda

in Dialysis Unite

AJM Bioorgchem UBCMCD

• Amanda explains that although water is essential for the

many chemical reactions that occur in the body, the
amount of water can become too high or too low, due to
various diseases and conditions.

• Because Michelle’s kidneys no longer perform dialysis,

she cannot regulate the amount of electrolytes or waste
in her body fluids.

• As a result, she has an electrolyte imbalance and a

buildup of waste products, so her body is retaining
water. Amanda then explains that the dialysis machine
does the work of her kidneys to reduce the high levels of
electrolytes and waste products.

AJM Bioorgchem UBCMCD

Review about Solutions

• solutions are everywhere around us. Most of the gases,

liquids, and solids we see are mixtures of at least one
substance dissolved in another.

• There are different types of solutions.
• The air we breathe is a solution that is primarily oxygen and

nitrogen gases.

• Carbon dioxide gas dissolved in water makes carbonated

drinks.

• When we make solutions of coffee or tea, we use hot water

to dissolve substances from coffee beans or tea leaves.

• In your medicine cabinet, the antiseptic tincture of iodine is a

solution of iodine dissolved in ethanol.

AJM Bioorgchem UBCMCD

• Solutions can be described by their concentration, which is the

amount of solute in a specific amount of that solution. These
relationships, which include mass % (m/m), volume % (v/v),
mass/volume % (m/v), and molarity (M), can be used to convert
between the amount of a solute and the quantity of its solution.

• Solutions are also diluted by adding a specific amount of solvent to

a solution.

• You will see also :
• In the processes of osmosis and dialysis, water, essential nutrients,

and waste products enter and leave the cells of the body.

• The kidneys utilize osmosis and dialysis to regulate the amount of

water and electrolytes that are excreted

AJM Bioorgchem UBCMCD

• Our body fluids contain water and dissolved

substances such as glucose and urea and
electrolytes such as K

, Na

, Cl

, Mg

, HCO

, and

HPO

-2

• Proper

amounts of each of these dissolved

substances and water must be maintained in the
body fluids.

• Small changes in electrolyte levels can seriously

disrupt cellular processes and endanger our
health.

AJM Bioorgchem UBCMCD

Defining a Solution and it’s derivatives

• Solutions: are homogeneous mixtures of

substances composed of at least one solute
and one solvent.

• homogeneous mixture: a uniform mixture

of only one phase

• solute: a substance that is dissolved in a

solvent (e.g., salt, NaCl)

• Solvent: the medium in which a solute is

dissolved; often the liquid component of a
solution (e.g., water)

• Please read the type of solute and solvents

in textbook , page (283-284)

AJM Bioorgchem UBCMCD

Water in the Body

• Water is one of the most common solvents in nature.
• The average adult is about 60% water by mass, and the

average infant about 75%.

• About 60% of the body’s water is contained within the cells as

intracellular fluids; the other 40% makes up extracellular
fluids, which include the interstitial fluid in tissue and the
plasma in the blood.

• These external fluids carry nutrients and waste materials

between the cells and the circulatory system.

AJM Bioorgchem UBCMCD

• Every day you lose between 1500 and 3000 mL of water from

the kidneys as urine, from the skin as perspiration, from the
lungs as you exhale, and from the gastrointestinal tract. Serious
dehydration can occur in an adult if there is a 10% net loss in
total body fluid; a 20% loss of fluid can be fatal. An infant
suffers severe dehydration with only a 5 to 10% loss in body
fluid.

• Water loss is continually replaced by the liquids and foods in the
• diet and from metabolic processes that produce water
• in the cells of the body.
• Table 9.2 lists the percentage by mass of water contained

in some foods.

AJM Bioorgchem UBCMCD

Table 9.2 :percentage of water in some foods

AJM Bioorgchem UBCMCD

How to make a solution

• It’s all about ( like dissolve like ) ,it means the polarity of

the solute and the solvent must be similar in order to
form solution. In other word the interaction between
them.

•

Solve Questions and problems page 286

AJM Bioorgchem UBCMCD

(a) (b) (c)

Figure 1 :

Like dissolves like. In each test tube, the

lower layer is CH

(more dense),

and the upper layer is water (less dense).
(a) CH

is nonpolar and water is polar; the two

layers do not mix. (b) The nonpolar solute I

(purple) is soluble in the nonpolar solvent CH

(c) The ionic solute Ni(NO

)

(green) is soluble in the

polar solvent water

Electrolytes and Nonelectrolytes

• Solutes can be classified by their ability to conduct an

electrical current.

• When electrolytes dissolve in water, the process of

dissociation separates them into ions forming solutions
that conduct electricity.

• When nonelectrolytes dissolve in water, they do not

separate into ions and their solutions do not conduct
electricity.

• To test solutions for the presence of ions, we can use an

apparatus that consists of a battery and a pair of
electrodes connected by wires to a light bulb.

AJM Bioorgchem UBCMCD

Types of Electrolytes

• Electrolytes can be further classified as

strong

electrolytes

weak

electrolytes.

• For a strong electrolyte, such as

sodium chloride (

NaCl)

, there is

100%

dissociation of the solute into ions.
When the electrodes from the

light

bulb

apparatus are placed in the NaCl

solution.

AJM Bioorgchem UBCMCD

A weak electrolyte :

• is a compound that dissolves in

water mostly as molecules. Only a

few

the

dissolved

solute

molecules

undergo

ionization,

producing a small number of ions in

solution .

• In an aqueous solution of the weak

electrolyte HF, a few HF molecules

ionize to produce H+ and F- ions. As

more H+ and F- ions form, some

recombine to give HF molecules.

AJM Bioorgchem UBCMCD

• A nonelectrolyte such as

sucrose (sugar) dissolves in
water

only

molecules,

which do not ionize.

• the light bulb does not glow,

because the solution does not
contain

ions

and

cannot

conduct electricity.

AJM Bioorgchem UBCMCD

Table 9.4: summarizes the classification of

solutes in aqueous solutions.

AJM Bioorgchem UBCMCD

• Example A: Indicate whether solutions of each of the

following contain only ions, only molecules, or mostly
molecules and a few ions. Write the equation for the formation
of a solution for each of the following:

• a. Na

(s), a strong electrolyte

• b. CH

OH(l), a nonelectrolyte .

SOLUTION

•

a. An aqueous solution of Na

(s) contains only the ions Na

and SO

•

b. A nonelectrolyte such as CH

(

)produces only molecules when it dissolves in

water.

AJM Bioorgchem UBCMCD

STUDy CHECK 1:

Boric acid, H

(s), is a weak electrolyte. Would you expect a boric acid solution to

contain only ions, only molecules, or mostly molecules and a few ions?

Equivalents

• Body fluids contain a mixture of electrolytes, such as Na

, Cl

, K

and Ca

. We measure each individual ion in terms of an equivalent

(Eq), which is the amount of that ion equal to 1 mole of positive or
negative electrical charge , or milliequivalent . 1 Eq= 1000 meq

AJM Bioorgchem UBCMCD

• For example: For ions, one equivalent (Eq) is equal to the

number of ions that carry 1 mol of charge.

• 1 mole of Na

ions and 1 mole of Cl

ions are each 1

equivalent because they each contain 1 mole of charge.

• For an ion with a charge of 2+ or 2-, there are 2

equivalents for each mole.

• In any solution, the charge of the positive ions is always

balanced by the charge of the negative ions. The
concentrations of electrolytes in intravenous fluids are
expressed in milliequivalents per liter (mEq/L); 1 Eq =
1000 mEq.

AJM Bioorgchem UBCMCD

• Also we can calculate gram equivalent of ion by divided the

molar mass of ion on the charge ion:

• The number of equivalents of a given ion per liter of solution

(Eq/l )can be found by

multiplying the molarity of the ion

(moles per liter) by the charge on the ion.

• For example, a solution containing 25 mEq/L of

and 4

mEq /L of

has a

total positive charge of 29

mEq /L. If Cl

the only anion, its concentration must be 29 mEq/L.

AJM Bioorgchem UBCMCD

Electrolytes in the Body Fluids

•

Electrolytes in the body play an

important role in maintaining the

proper function of the cells and

organs in the body.

•

Typically, the electrolytes

sodium,

potassium,

chloride,

and

bicarbonate

are measured in a

blood test.

•

Sodium ions regulate the water

content in the body and are

important

carrying

electrical

impulses through the nervous system.

•

Table 9.6

gives the concentrations of

some typical electrolytes in blood

plasma .

•

There is a charge balance because

the total number of positive charges

is equal to the total number of

negative charges.

AJM Bioorgchem UBCMCD

• Potassium ions

are also involved in the transmission

of electrical impulses and play a role in the

maintenance of a regular heartbeat.

• Chloride ions

balance the charges of the positive

ions and also control the balance of fluids in the

body.

• Bicarbonate

is important in maintaining the proper

pH of the blood.

• Sometimes when vomiting, diarrhea, or sweating is

excessive, the concentrations of certain electrolytes

may decrease. Then fluids such as Pedialyte may

be given to return electrolyte levels to normal.

AJM Bioorgchem UBCMCD

• The

concentrations

electrolytes present in body

fluids and in intravenous fluids

given to a patient are often

expressed in milliequivalents per

liter (mEq/L) of solution.

•

For

example,

one

liter

Pedialyte contains the following

electrolytes: Na

45 mEq, Cl

mEq, and citrate

30 mEq.

• The use of a specific intravenous

solution

depends

the

nutritional, electrolyte, and fluid

needs of the individual patient.

AJM Bioorgchem UBCMCD

• Examples of various types of solutions are given in

Table 9.7.

AJM Bioorgchem UBCMCD

Types of Solution

• We already talk about solutions …
• In a solution, the components cannot be distinguished

one from the other. Syrup is a solution of sugar and

water: The sugar cannot be distinguished from the

water.

• The solution appears transparent, although it may have

a color. The particles are so small that they go through

filters and through

semipermeable membranes.

• A semipermeable membrane allows solvent molecules

such as water and very small solute particles to pass

through, but doesn’t allow the passage of large solute

molecules.

AJM Bioorgchem UBCMCD

Colloids Solutions

• The

particles in a colloid

are much larger than

solute particles in a solution.

• Colloidal particles are large molecules, such as

proteins, or groups of molecules or ions.

• Colloids, similar to solutions, are homogeneous

mixtures that do not separate or settle out.

• Colloidal particles are small enough to pass

through filters, but too large to pass through

semipermeable membranes.

AJM Bioorgchem UBCMCD

TABLE 1: Examples of Colloids

AJM Bioorgchem UBCMCD

Suspensions Solutions

• Suspensions are

heterogeneous

that are very

different from solutions or colloids.

• The particles of a suspension are so large that they

can often be seen with the naked eye.

• They are trapped by filters and semipermeable

membranes.

• You can find suspensions among the medications in

a hospital or in your medicine cabinet.

• These

include

Kaopectate,

calamine

lotion,

antacid mixtures, and liquid penicillin.

AJM Bioorgchem UBCMCD

• shake well before using so that the particles form a

suspension.

• Water-treatment plants make use of the properties

of suspensions to purify water.

• Aluminum sulfate or iron(III) sulfate are added to

untreated water, they react with impurities to form

large suspended particles called floc.

• (Table 2 )compares the different types of mixtures

AJM Bioorgchem UBCMCD

Table 2 :Comparison of Solutions, Colloids, and Suspensions

AJM Bioorgchem UBCMCD

If you have mixture

AJM Bioorgchem UBCMCD

Figure 1 : Properties of different types of mixtures: (a)suspensions settle out; (b) suspensions are
separated by a filter; (c) solution particles go through a semipermeable membrane, but colloids and
suspensions do not

Colloids and Solution in the body

• In the body, colloids are retained by semipermeable

membranes.

• For example, the

intestinal lining

allows solution

particles to pass into the blood and lymph circulatory

systems.

• However,

the colloids from foods are too large to

pass through the membrane

and they remain in the

intestinal tract.

• Digestion breaks down large colloidal particles, such

as starch and protein

, into smaller particles, such as

glucose and amino acids

that can pass through the

intestinal membrane and enter the circulatory system.

AJM Bioorgchem UBCMCD

• Certain foods, such as bran, a fiber, cannot be

broken down by human digestive processes, and

they move through the intestine intact.

• Because large proteins, such as enzymes, are

colloids, they remain inside cells.

• However, many of the substances that must be

obtained by cells, such as

oxygen, amino acids,

electrolytes, glucose, and minerals

, can pass

through cellular membranes.

• Waste products, such as urea and carbon dioxide,

pass out of the cell to be excreted.

AJM Bioorgchem UBCMCD

Osmotic Pressure

• The movement of water into and out of the cells of

plants as well as the cells of our bodies is an
important biological process that also depends on
the solute concentration.

• In a process called osmosis, water molecules move

through a semipermeable membrane from the
solution with the lower concentration of solute into a
solution with the higher solute concentration

AJM Bioorgchem UBCMCD

In an osmosis apparatus,
water is placed on one side of a semipermeable membrane
and a sucrose (sugar) solution on the other side.

The

semipermeable

membrane allows water

molecules to flow back and

forth but blocks the sucrose

molecules

because

they

cannot pass through the

membrane.

AJM Bioorgchem UBCMCD

• Because the sucrose solution has a higher solute

concentration, more water molecules flow into the

sucrose solution than out of the sucrose solution.

• The volume level of the sucrose solution rises as the

volume level on the water side falls.

• The increase of water dilutes the sucrose solution to

equalize (or attempt to equalize) the concentrations

on both sides of the membrane.

• Eventually the height of the sucrose solution creates

sufficient pressure to equalize the flow of water

between the two compartments. This pressure, called

osmotic pressure.

• The osmotic pressure depends on the

concentration of

solute particles in the solution

• The greater the number of particles dissolved, the higher

its osmotic pressure.

• the sucrose solution has a higher osmotic pressure than

pure water, which has an osmotic pressure of zero.

• Water flows into the solution with a higher solute

concentration until the flow of water becomes equal in

both directions.

• In a process called

reverse osmosis

, a pressure greater

than the osmotic pressure is applied to a solution so that

it is forced through a purification membrane

AJM Bioorgchem UBCMCD

Isotonic Solutions

• Because the cell membranes in

biological systems are semipermeable, osmosis is an

ongoing process. The solutes in body solutions such as

blood, tissue fluids, lymph, and plasma all exert

osmotic pressure.

• Most intravenous (IV) solutions used in a hospital are

isotonic solutions, which exert the same osmotic

pressure as body fluids such as blood.

• The most typical isotonic solutions are 0.9% (m/v)

NaCl solution, and 5% (m/v) glucose

AJM Bioorgchem UBCMCD

• Although they do not contain

the same kinds of particles, a
0.9% (m/v) NaCl solution as well
as a 5% (m/v) glucose solution
are both 0.3 M (Na

and Cl

ions

or glucose molecules).

AJM Bioorgchem UBCMCD

Figure :2 (a) In an isotonic solution, a red blood

cell retains its normal volume.

AJM Bioorgchem UBCMCD

A red blood cell placed in an isotonic
solution retains its volume because there is
an equal flow of water into and out of the
cell (see Figure 2a).

(Figure 2a)

AJM Bioorgchem UBCMCD

Hypotonic Solutions

• If a red blood cell is placed in a

solution that is not isotonic, the

differences in osmotic pressure

inside and outside the cell can

drastically alter the volume of the

cell.

• When a red blood cell is placed

in a hypotonic solution, which

has a lower solute concentration

water flows into the cell by

osmosis.

•

The increase in fluid causes the

cell to swell, and possibly burst—

a process called hemolysis (see

Figure 2b).

AJM Bioorgchem UBCMCD

(Figure 2b).

hypertonic solution

• If a red blood cell is placed in a

hypertonic solution, which has a higher
solute concentration, water flows out of
the cell into the hypertonic solution by
osmosis.

•

Suppose a

red blood cell

is placed in a

10% (m/v) NaCl solution. Because the
osmotic pressure in the red blood cell is
the same as a 0.9% (m/v) NaCl solution,
the 10% (m/v) NaCl solution has a much
greater osmotic pressure.

• As water leaves the cell, it shrinks, a

process called

crenation

(see Figure.2c)

AJM Bioorgchem UBCMCD

(Figure.2c)

• A similar process occurs when making pickles,

which uses a hypertonic salt solution that

causes the cucumbers to shrivel as they lose

water.

AJM Bioorgchem UBCMCD

SAMPLE PROBLEM

• Describe each of the following solutions as isotonic,

hypotonic, or hypertonic. Indicate whether

a red

blood cell

placed in each solution will undergo

hemolysis, crenation, or no change.

• a. 5% (m/v) glucose solution
• b. 0.2% (m/v) NaCl solution
• SOLUTION:

• Study Case 2: What will happen to a red blood cell

placed in a 10% (m/v) glucose solution?

AJM Bioorgchem UBCMCD

Dialysis

AJM Bioorgchem UBCMCD

o Dialysis is a process that is similar to

osmosis. In dialysis, a semipermeable
membrane,

called

dialyzing

membrane,

permits

small

solute

molecules and

ions

as well as

solvent

water

molecules to pass through, but it

retains

large particles

, such as

colloids.

o Dialysis is a way to separate

solution

particles from

colloids.

o Suppose we fill a cellophane bag with

a solution containing NaCl, glucose,
starch, and protein and place it in pure
water.

AJM Bioorgchem UBCMCD

• Cellophane is a dialyzing membrane, and

the

sodium ions

chloride ions

, and

glucose

molecules will pass through it into the

surrounding water.

• However, large colloidal particles, like

starch and protein

, remain inside.

• Water

molecules

will

flow

into

the

cellophane bag.

•

Eventually the concentrations of

sodium

ions,

chloride ions

, and

glucose

molecules

inside and outside the dialysis bag become

equal.

• To remove more

NaCl

glucose,

the

cellophane bag must be placed in a fresh

sample of pure water.

Dialysis by Kidneys and Artificial Kidney

AJM Bioorgchem UBCMCD

The fluids of the body undergo dialysis by
the membranes of the kidneys, which
remove

waste materials

excess salts

and

water.

In an adult, each kidney contains about

million nephrons

At the top of each nephron, there is a

network of arterial capillaries called the
glomerulus.

As blood flows into the glomerulus, small

particles, such as

amino acids,

glucose,

urea,

wate

r, and

certain ions,

will move

through the capillary membranes into the
nephron.

• As this solution moves through the

nephron, substances still of value

to the body

(

such as

amino

acids,

glucose

certain ions

and

99% of the water

) are reabsorbed.

The major waste product,

urea,

excreted in the

urine.

AJM Bioorgchem UBCMCD

Hemodialysis

•

If the kidneys fail

to dialyze waste products, increased

levels of

urea

can become life-threatening in a

relatively short time.

• A person with kidney failure must use an artificial

kidney, which cleanses the blood by hemodialysis.

• A typical artificial kidney machine contains a large

tank filled with water containing selected electrolytes.

• In the center of this dialyzing bath (

dialysate)

, there is

a dialyzing coil or membrane made of cellulose tubing.

AJM Bioorgchem UBCMCD

• As the patient’s blood flows through the

dialyzing coil, the highly concentrated waste

products dialyze out of the blood.

• No blood is lost because the membrane is not

permeable

to large particles

such as

red blood

cells.

AJM Bioorgchem UBCMCD

Dialysis patients do not produce much urine. As a result,

they retain large amounts of water between dialysis

treatments, which produces a strain on the heart.

The intake of fluids for a dialysis patient may be restricted

to as little as a few teaspoons of water a day.

In the dialysis procedure, the pressure of the blood is

increased as it circulates through the dialyzing coil so

water can be squeezed out of the blood. For some

dialysis patients, 2 to 10 L of water may be removed

during one treatment.

Dialysis patients have from two to three treatments a

week, each treatment requiring

about 5 to 7 h

Some of the newer treatments require less time.

For many patients, dialysis is done at home with a home

dialysis unit.

AJM Bioorgchem UBCMCD

Hemodialysis

AJM Bioorgchem UBCMCD

Summary

AJM Bioorgchem UBCMCD

QUESTIONS AND PROBLEM (H.W)

• 1. Identify the following as characteristic of a solution, a colloid,

or a suspension:

a. a mixture that cannot be separated by a semipermeable

membrane

b. a mixture that settles out upon standing.

• 2. Identify the following as characteristic of a solution, a colloid, or

a suspension:

a. Particles of this mixture remain inside a semipermeable

membrane but pass through filters.

b. The particles of solute in this solution are very large and visible .

• 3. A 10% (m/v) starch solution is separated from a 1% (m/v)

starch solution by a semipermeable membrane. (Starch is a

colloid.)

a. Which compartment has the higher osmotic pressure?

b. In which direction will water flow initially?

c. In which compartment will the volume level rise?

AJM Bioorgchem UBCMCD

Thank You For your

Attention

AJM Bioorgchem UBCMCD