1.
SOLUTIONS
’ A homogeneous mixture of two or more substances is known as Solution.
’
OR
A homogeneous mixture of chemical substances , which has same chemical
composition and physical properties is called Solution
In solution , the mixing substances do not react chemically with each other but
only physical changes take place , they do not allow light to scatter
EXAMPLES: brass , sugar in water etc
SYRUPS: the aqueous solution containing sugars (sucrose)
EXAMPLE : Acacia syrups
EXILIRS: some solution contains some alcohols , sweetened hydro-alcoholic
solutions
EXAMPLE : diphenylhydramine HCl exilirs
SPIRITS: solutions of aromatic materials , if solvent is alcohols or aromatic waters
and if solution is aqueous
TINCTURES: solution prepared by active constituents of crude oils or are fluid
extracts , depending upon their method of preparation and concentration
Tinctures may be also solutions of chemical substances dissolved in alcohols or in
hydro-alcoholic solutions
INJECTIONS: Certain solutions prepared to be sterile and pyrogen free and
intended for parental administration although other examples could be citied it is
apparent that a solution , as a distinct type of pharmaceutical preparation , it is
must further defined that physio-chemical definition of term solution
COMPOSITION OF SOLUTION
Solution is usually composed of two components and are known as Binary
solutions
i.e Solute and Solvent
Solute: The component of the solution which is present in small quantity and is in
dissolved form (sugar)
Solvent: The component of the solution which is present in larger quantity and
dissolves the solute (water)
SYSTEM AND PHASE

2.
A system is a bounded space or a definite quantity of substance , which is under
observation or experiment .
A distinct system’s homogeneous part separated by definite boundaries from
other parts of the system is called phase.
TYPES OF DISPERESED SYSTEM ON SOLUTION
A system in which substance is dispersed as particle throughout the dispersion
medium is called dispersed medium
A solution which may have homogeneous or heterogeneous dispersion with
particles between two solutions is called Dispersion.
On the basis of dispersed particles or solute particles the dispersion may be
divided into three types :
. True solution
. Colloidal solution
. Coarse solution
1- TRUE SOLUTION
A solution resulted due to the homogeneous dispersion of ions or a molecule of one
component throughout the other is called True solution
. The particle size in true solution is smooth and is less than 40A
The example of true solution with ionic dispersion is solution on NaCl in water and
that of molecular dispersion is solution of sucrose in water
. In true solution , when solute is added to the solvent the volume of the solvent
remains the same , because the solute molecules adjust themselves in the
intermolecular spaces of solvent
2- COLLOIDAL SOLUTION
A solution which my be homogeneous or heterogeneous dispersion with the particle
size
between that of true and coarse dispersion
. The particle or molecular size is between 10A or 2000A
The example of colloidal solution with homogeneous mixture is that of acacia
(sodium carboxymethyl cellulose) in water and a colloidal solution with
heterogeneous mixture is that of silver proteinate in water
3- COARSE SOLUTION

3.
A solution in which particle size or solute size is the largest is called coarse solution /
dispersion
. The particle or solute size in such dispersion is larger than 2000A
As the particle size is very large , so cannot adjust themselves between the
intermolecular forces of solvent
Its example is Emulsions (e.g Milk , Oil+ Water) and Suspensions
This dispersion cannot pass through ordinary filter paper
TYPES OF SOLUTION
PROPERTIES OF SOLUTION (Physical)
On the physical basis the properties of solution can be divided into three main
types :
. Additive properties
. Constitutive properties
. Colligative properties
1- Additive properties
The physical properties which upon the sum of the properties of all the constituents
of the solution
EXAMPLES: mass , volume, molecular weight etc
2- Constitutive properties
The physical properties which depend upon the arrangement of atoms within the
molecules are called constitutive properties
EXAMPLES: refractive index , electrical properties , solubility , surface tension and
interfacial characters etc

4.
3- Colligative properties
The physical properties of the solution which depend upon the Na of atoms of the
solution , are called colligative properties
Some important colligative properties are
1. Elevation of B.P
2. Lowering of M.P
3. Depression i n F.P
4. Osmotic pressure
The values of colligative properties are approximately same for the solution of the
same concentration
Types of solutions
The solutes (whether they are liquid , solid or gaseous phase) are classified into
two types on the basis of their electrical properties:
Electrolytes
Non - electrolytes
Electrolytes
Those solutions which are ionized in the solution and conduct electricity are known
as electrolytes
Such solutions show greater colligative properties as compared to the others with
the same concentration
Electrolytes are further divided into two classes :
Strong electrolytes :
Those electrolytes which ionize completely in the solution are called as strong
electrolytes
EXAMPLES: NaCl , Na2SO4 , HCl etc
Weak electrolytes:
Weak electrolytes ionize in the solution partially
EXAMPLES : Ephedrine , Phenobarbital etc
Non - Electrolytes
Those solutes which do not ionize in the solutions and cannot conduct electricity are
called non-electrolytes
EXAMPLES: Sucrose , Urea and Naphthalene etc
UNSATURATED SOLUTION : A solution in which more solute is present than the
solvent can afford and the solute is not dissolved in the solution completely
SATURATED SOLUTION : The one where concentration is at maximum , no more

5.
solute is able to dissolve at a given temperature
. It represents an equilibrium
. The rate of dissolving = The rate of crystallization
Salt continues to dissolves ; but crystallizes t the same rate or under those
conditions the number of molecules leaving solute = the number of molecules
returning to the solid phase i-e solute
SUPER-SATURATED SOLUTION: A solution that contain relatively larger amount
of solute than that required for saturation , it is prepared by heating and adding
more and more solute
CONCENTRATION EXPRESSION
The amount of solute present in a given amount of the solution is called as
concentration expression
A solution containing relatively lower amount of solute is known as Dilute solution
while
A solution containing relatively higher amount of solute is known as Concentrated
solution
Concentration of solution may either be expressed in terms of quantity of solute in
a definite volume in solution or as the quantity of solute in a definite mass of
solvent or solution
There are several ways of expressing concentration of the solution , some of them
are as follow :
1- Percentage Expression
2- Molarity
3- Normality
4- Molality
5- Mole fraction
6- Parts per million
7- Percent by volume
7- Percent by weight
8- Percent weight in volume
9- Milligram percent
1- Percentage Expression :
It is defined as the specific amount of solutes present in 100 gm of solution
Following are three types of percentage expression :
(a) %age w/w : It is the weight of solute as present in total weight of solution

6.
%age of solute = weight of solute * 100
weight of solution
Example : 10% w/w aqueous solution of glycerine means 10g of glycerine
dissolved in enough water to make it 1000 grams
(b) %age v/v : It is the volume of solute as present in total volume of solution
%age of solute = volume of solute * 100
Volume of solution
Example : 10% v/v aqueous ehthanoic solution means 10 ml of ethanol dissolved
in enough water o make it 1 liter
(c) %age v/w : It is the volume of solute as present in total weight of solution
%age of solute = volume of solute * 100
weight of solution
Example : 10% v/w aqueous glycerine means 10 ml of glycerine dissolved in
enough water to make it 1000 grams of solution
(d) %age w/ v : It is the weight of solute as present in total volume of solution
%age of solute = weight of solute * 100
volume of solution
Example : 10% w/v aqueous NaCl solution means 10 grams dissolved in enough
water to make it 1 liter
2- Molarity and Normality :
all solution of same molarity contains the same no. of solute molecules in definite
volume of solution
In case of more than one solute , it may have different molar concentration of
every solute
EXAMPLE :
MOLARITY: A solution can be 0.001M phenobarbital and 0.1M NaCl w.r.t 1 liter of
solution prepared by 0.001 mole of phenobarbital (0.001 mol * 263 g/mol =
0.2323g) and 0.1 mole of NaCl (0.1 mol * 58.45 g/mol = 5.845g ) to enough water
to make 1000 ml of solution
NORMALITY: A molar solution of NaCl is 1M w.r.t both Na+ and Cl- ions , whereas
molar solution of Na2CO3 is 1M w.r.t Na+ is 2M and that of carbonate is 1M
A molar solution of NaCl is 1 normal with respect to both ,however, that of Na2CO3
is 2M w.r.t both
Molarity :
It is defined as the number of moles of solutes dissolved per liter(1l= 1000g) of
solution
Molarity= no. of moles of solutes

7.
Volume of solution (in liters)
Where no. of moles = given weight
Molar mass
It is represented by M and its units are mol/liters.
EXAMPLE :
Determine the molarity of 41.50g FeSO4 ?
Moles of FeSO4 = grams of FeSO4 = 41.50 = 0.2732
Mol. Weight 151.9
M = 0.2732 = 0.2732
1 liter
Normality :
The number of grams equivalent of solute present per liter of solution
Normality : no. of grams equivalent of solute
Volume of solution (in liters)
Where no. of gm equivalent = weight of substance
Equivalent weight
Equivalent weight : no. of parts by weight of the substance combines with
one part with weight of replacement H+ or OH- or number of +ive charges on
element
Equivalent weight = molecular weight
Acidity or basicity
EXAMPLE:
Calculate the normality of H2SO4 solution where 98g of H2SO4 is dissolved in 500
liters?
Equivalent weight of H2SO4 = 49
No. of grams equivalent of H2SO4 = 98/49 = 2
Volume of solution = 500cm3 = 0.5 liters
Normality = 2/0.5 = 4N
DISADVANTAGES:
Molarity and normality has a disadvantage of changing of value with the
temperature
Because the volume is a temperature dependent value because of the contraction
and expansion of liquid.
MOLALITY

8.
The number of moles of solute per kilogram of solvent
it is represented by m and its unit is mol/kg
m = no. of moles
Kilogram of solvent
A molal solution is prepared in terms of weight units and does not have
disadvantages just discussed above (temperature) therefore , molal concentration
appear more frequent than molarity and normality in theoretic studies
EXAMPLE :
1- Calculate the molality of 6.4 grams of methanol dissolved in 50 moles of
water?
a) 0.040 m b) 0.22 m
c) 0.064 m d) 0.11 m
m =moles of solute = 6.4/32
Kg of solvent 50*18
2- Find the molality
Grams of solution = volume * density
1000*1.0375= 1037.5
Grams of solvent = grams of solution - grams of FeSO4
1037.5- 41.5 = 996 g
Molality = moles of FeSO4 = o.2732 = 0.2743
kg of solvent 0.996
3- MOLE FRACTION
The ratio of no. of moles of one constituents to no. of moles of all the
constituents in the solution is called mole fraction
It is denoted by “X”
Mole fraction is frequently used in experimentation involving theoretical
consideration
It gives a measure of each constituent in a solution
It is expressed for a system of two constituents which are
X1 is the MF of solvent
X2 is the MF of solute
n1 is the no. of moles of solvent
n2 is the no. of moles of solute

9.
X1 = n1 X2 = n2
n1 + n2 n1+n2
X1 + X2 = 1
Sum of MF of solute and solvent is always equals to unity
So mole percentage will always be equal to 100%
In a solution containing 0.01 mole of solute and 0.04 moles of solvent the MF of
X2 will be 0.20
We know that the MF of two constituents must be equal to 1 so the MF of solvent
will be 0.80
The mole percent of solute will be 20% and that of solvent will be 80%
The manner in which MF is defined allows one to express the relationship between
the no. of solute and solvent molecules in a simple direct way
It means two out of every 10 molecules in a solution are solute molecules and that
many of the solute and solvent properties are directly related to the MF of the
solution
The partial vapor pressure above a solution brought about the pressure of
volatile solute = the vapor pressure of pure solute * the MF of the solute in
solution
EXAMPLE :
Moles of water = 996 = 55.5 moles
18.02
Moles of FeSO4 = 41.50 = 0.2732
151.9
MF of FeSO4 = 0.2732 = 0.049
0.2732+55.5
MF of water = 55.5 = 0.0951
0.2732+55.5
Note that X1 + X2 = 1
So mole percent will also 100%
5- PARTS PER MILLION/BILLION
it is another way of expressing concentration in a particular way that very dilute
solution can also be expressed e.g to describe the impurities in a solution
ppm denotes the amount of given substance in total amount of 1000000 of
solution e.g one mg per kg i.e 1 part in 106
ppb denotes the amount of given substance in a total amount 1000000000 of
solution e.g 0.001 mg per kg of solution i.e 1 part in 109

10.
Ppm/ppb = mass of A in solution * 106/109
Total mass of solution
EXAMPLE : if 3.6 mg of Hg is detected of 200g sample of H2O from lake
Saif-ul-Malook what is its ppm concentration ?
Ppm = 0.0036 * 106 = 18ppm
200
CHANGING OF MOLARITY INTO MOLALITY