CHRIST JYOTI SR.

SEC. SCHOOL, SATNA

(M.P.)

SESSION: 2025-26

CHEMISTRY
PROJECT

Internal Examiner: Compiled by:

Mrs. Neelesh Garg Kanha Tripathi
Subject: Chemistry Roll number: 8
Class: XII Red
 PERMISSION LETTER
To
Mrs. Neelesh Garg
Subject: Permission to Submit Chemistry Project
Respected Madam,
I am Kanha Tripathi, a student of Class 12, studying in
the
Science stream. I am working on a Chemistry project as
a part of our academic curriculum for the current
academic session.
I kindly request your permission to carry out and submit
this project under the guidance of my Chemistry teacher.
The project will be submitted in the prescribed format
and within the given timeline.
I assure you that all the necessary precautions and
academic. integrity will be maintained while preparing
this project. I hope for your kind permission and support.

Thanking you,
Yours obediently,
Kanha Tripathi
Class 12 - Red
Roll No: 08
 ACKNOWLEDGEMENT
I would like to sincerely thank my Chemistry teacher, Mrs.
Neelesh Garg, for her valuable guidance, motivation, and
continuous support that helped me complete this project with
confidence and clarity.
This project reflects both her dedicated teaching and my
sincere efforts to learn, research, and present the topic in the
best possible manner.
Kanha Tripathi
Class 12 - Red
Roll No: 08
 Certificate
This is to certify that Kanha Tripathi, a student of
Class12 Red, has successfully completed the Chemistry
project under the guidance of Mrs. Neelesh Garg,
during the academic year2025-26.
The work presented in this project is the student's
original effort and has been carried out with sincerity
and dedication.
We wish him all the best for future academic
success.

Internal Examiner External examiner

Mrs. Neelesh Garg
 INDEX
1. Colligative Properties
2. Relative Lowering Of Vapour Pressure
3. Elevation In Boiling Point
4. Depression In Freezing Point
5. Osmosis and Osmotic Pressure
6. Bibliography

Colligative properties
The dilute solutions show more or less ideal behavior and
obey Raoult’s law. The properties of dilute solutions which
depend only on number particles of solute present in the
solution and not on their identity are called colligative
properties.
Here the solute is assumed to be non-volatile.
The various colligative properties are:
 Lowering of vapour pressure
 Elevation of boiling point
 Depression of freezing point
 Osmotic pressure
 Lowering of vapour pressure
• when a non-volatile solute is dissolved in a liquid, the
vapour pressure of the solution becomes lower than the
vapour pressure of the pure solvent.
• Let us consider n moles of a non-volatile solute is dissolved
in N moles of a volatile solvent. Then mole fraction of the
solvent, X 1 = N/(n+N) and mole fraction of the solute, X2 = n
/(N +n).
• According to Raoult's law, the vapour pressure of a solvent
(P1) in an ideal solution is given by the expression;
P1 = X1 P10......................... (1)
where P10 is the vapour pressure of the pure solvent. Since X1 +
X 2 = 1, Eq. 1 may be written as

Equation 3 can be stated as

“The relative lowering of vapour pressure of
a solution containing a non-volatile solute is
equal to the mole fraction of the solute
present in the solution.'
• Since mole fraction of the solute, X2 is given by n/(N+n),
Equation (3) may be
expressed as
• From Equation (4) that the lowering of vapour pressure of a
solution depends upon the number of moles (and hence on
the number of molecules) of the solute and not upon the
nature of the solute dissolved in a given amount of the
solvent.
Hence, lowering of vapour pressure is a colligative
property.

Determination of Molar Masses from Lowering of Vapour

Pressure
• It is possible to calculate molar masses of non-volatile non-
electrolytic solutes by measuring vapour pressures of their
dilute solutions.
• Suppose, a given mass, w gram, of a solute of molar mass
m, dissolved in W gram of solvent of molar mass M, lowers
the vapour pressure from P10 to P1. Then, by equation (4)

Since in dilute solutions, n is very small as compared to

N, Equation (5) may be put in the approximate form
 Figure 1Relative lowering of vapour pressure

 Applications of relative lowering of vapour pressure:

1. Determination of Molar Mass of Solute:-

 By measuring the lowering of vapour pressure of a solution,

we can calculate the molar mass (molecular weight) of an
unknown solute.
 This is especially useful in chemistry labs for non-volatile
solutes.
2. Preservation of Food:-

 Adding salt or sugar to food lowers the water's vapour pressure,

reducing moisture and making it harder for bacteria and fungi
to survive.
 Example: Pickling with salt or making jams with sugar.
3. Antifreeze in Car Radiators:-
 Ethylene glycol is added to water in radiators. It lowers the
vapour pressure, which helps raise the boiling point and lower
the freezing point.
 This keeps the engine running in hot and cold weather.

Elevation of boiling point

• The boiling point of a liquid is the temperature at which its
vapour pressure becomes equal atmospheric pressure. Since

• Addition of a non-volatile solute lowers the vapour pressure of

the solvent

• The vapour pressure of a solution is always lower than that of

the pure solvent, and hence it must be heated to a higher
temperature to make its vapour pressure equal to atmospheric
pressure.

• Thus the solution boils at a

higher temperature than the
pure solvent. If Tb0 is the
boiling point of the solvent and
 Tb is the boiling point of the solution, the difference in boiling
points (ΔTb) is called the elevation of boiling point
ΔTb= Tb-Tbo

Tbα m

ΔTb = Kb x m

Kb: molal elevation constant and

m : molality of the solution
Figure 2 Elevation of boiling point

Boiling point elevation in a dilute solution is directly

proportional to the number of moles of the solute dissolved
in a given amount of the solvent and is quite independent of
the nature of the solute. Hence, boiling point elevation is a
colligative property.

• Molal boiling point elevation constant or ebullioscopic

constant of the solvent, is defined as the elevation in boiling
point which may theoretically be produced by dissolving one
mole of any solute in 1000 g of the solvent.
 Where, m1 = molecular weight of solute and w and W are
weights of solute and solvent.

Applications of elevation of boiling point: -

1. Cooking and Food Science:

- High-Altitude Cooking: At higher elevations, the
atmospheric pressure is lower, which can affect boiling
points. Cooking times for boiling foods may need to be
adjusted since water boils at a lower temperature, leading to
longer cooking times.
- Preservation: Understanding boiling point elevation helps in
canning and preserving food by ensuring that the
temperature is sufficient to kill bacteria and prevent spoilage.

2. Chemical and Pharmaceutical Industries:

- Solution Preparation: In laboratories, boiling point elevation
is used to determine the molar mass of solutes by measuring
the change in boiling point when a solute is dissolved in a
solvent.
- Drug Formulation: The solubility and stability of drugs can
be affected by changes in boiling points, which is crucial for
formulating effective medications.

3. Environmental Science:
- Weather Prediction: Boiling point elevation concepts are
applied in meteorology to understand the behavior of water
 and its phase changes in different atmospheric conditions,
aiding in weather modeling and predictions.

4. Cryogenics and Refrigeration:

- Refrigerants: Understanding boiling point elevation is
essential in the design of refrigerants, which often require
specific boiling points to operate efficiently in cooling
systems.

DEPRESSION OF FREEZING POINT

• Freezing point is the temperature at which solid and liquid
states of a substance have the same vapour pressure.

• It is observed that the freezing point of the solution (T f)

containing non volatile
solute is always less than
the freezing point of
the pure solvent (Tf0).
Thus, Tf0 – Tf = ΔTf
It can be seen that Tf α m
or, ΔTf = Kf x m
 Figure 3 Depression of freezing point

Kf : molal freezing point depression constant of the

solvent or cryoscopic constant
m : molality of the solution
• Molal freezing point depression constant of the solvent or
cryoscopic constant, is defined as the depression in freezing
point which may theoretically be produced by dissolving 1
mole of any solute in 1000g of the solvent.

where m1 = molecular weight of solute and w and W are weights of

solute and solvent

• Thus, freezing point depression of a dilute solution is directly

proportional to the number of moles of the solute dissolved in a
 given amount of the solvent and is independent of the nature of
solute.
 Applications of Depression of boiling point: -
1.In areas with lower temperatures, sodium chloride is
spread over the roads. This is done in order to lower the
freezing point of water. This also helps in preventing the
build-up of ice.
2.Ethylene glycol and water are generally used to make
radiator fluids that are used in many automobiles.This
helps in preventing the freezing of the radiator during the
winter season.
3. The freezing point depression formula can be used to
determine the molar mass of a given solute.

Figure 4Molal Boiling Point Elevation and Freezing Point Depression Constants for Some Solvents
 OSMOSIS AND OSMOTIC PRESSURE
The phenomenon of the passage of pure solvent from a region
of lower concentration (of the solution) to a region of its
higher concentration through a semi-permeable membrane is
called osmosis.
The difference in the pressure between the solution and the

solvent system is called osmotic pressure. It is the excess

pressure which must be applied to a solution in order to

prevent flow of solvent into the solution through the semi-
permeable membrane.
The flow will continue till the equilibrium is attained. The flow
of the solvent from its side to solution side across a
semipermeable membrane can be stopped if some extra
pressure is applied on the solution. This pressure that just stops
the flow of solvent is called osmotic pressure of the solution.
The flow of solvent from dilute solution to the concentrated
solution across a semipermeable membrane is due to osmosis.
The important point to be kept in mind is that solvent molecules
always flow from lower concentration to higher concentration
of solution. The osmotic pressure has been found to depend on
the concentration of the solution.
Osmotic pressure(π) is proportional to the molarity, C of the
solution at a given temperature T. Thus:
 π=CRT
π = (n2 /V) R T
Here V is volume of a solution in litres containing n 2 moles of
solute. If w2 grams of solute, of molar mass, M2 is present in
the solution, then n2 = w2 / M2 and we can write,

Isotonic Solutions: A pair of solutions having same osomotic

pressure is called isotonic solutions.
Hypertonic solution : A solution having osmotic pressure higher
than that of another solution is said to be hypertonic.

Hypotonic solution : A solution having osmotic pressure lower

than that of another solution is said to be hypotonic solution with
that solution.
Figure 5 Isotonic, Hypertonic, Hypotonic

Reverse Osmosis
When a solution is separated from pure water by a
semipermeable membrane, water moves towards solution on
account of osmosis. This process continues till osmotic pressure
becomes equal to hydrostatic pressure or osmosis can be
stopped by applying external pressure equal to osmotic pressure
on solution. If external pressure greater than osmotic pressure is
applied, the flow of solvent molecules can be made to proceed
from solution towards pure solvent, i.e., in reverse direction of
the ordinary osmosis. This type of
osmosis is termed reverse
osmosis. Reverse osmosis is used
for the desalination of sea water
for getting fresh drinking water.
 Applications of osmosis: -
1. Transportation within cells
Diffusion and active transport are two more cellular transport
processes that are closely related to osmosis. When combined, these
mechanisms guarantee the proper distribution of necessary materials
like ions, nutrients, and waste products both inside and between
cells.
2. Osmolarity of blood and kidneys
The control of blood osmolarity depends on osmosis. Osmosis, for
instance, is used by the kidneys to reabsorb water only when
necessary and to keep the body’s water balance. The nephrons,
which are responsible for producing urine, carry out this process by
reabsorbing water into circulation and adjusting solute
concentrations.

BIBLIOGRAPHY

 NCERT Chemistry Textbook – Class XII

Chapter : Solutions
Publisher: National Council of Educational Research and
Training (NCERT)
 Pattanayak, C. J. (2015). Colligative Property. Retrieved
from https://www.slideshare.net/slideshow/colligative-property-
ade-bychinmay-jagadev-pattanayak/56894098
 ClassNotes.org.in. (n.d.). Colligative Properties -
Chemistry, Class 12, Solutions. Retrieved from
https://classnotes.org.in/class12/chemistry12/solutions/colliga
tive-properties/Class Notes
 NEET Guide. (n.d.). Colligative Properties: Comprehensive
NEET Chemistry Notes. Retrieved from
https://neet.guide/ncert-solutions/chemistry/class-xii-
solutions/colligative-propertiesneet.guide+1
 HSC Projects. (n.d.). Chemistry Project On Colligative
Properties Of Class 12th. Retrieved from
https://hscprojects.com/chemistry-project-on-colligative-
properties-of-class-12th/HSC Projects
 Vedantu. (n.d.). Colligative Properties: Definition, Types,
Formulas & Examples. Retrieved from
https://www.vedantu.com/chemistry/colligative-
propertiesvedantu.com
THANK
YOU