hot ice class 12 investigatory project chemistry best

i came to this site to search for good projects but made my own , uploading so that you all dont have a hard time .
note : the index and the front page is not complete as the page number formats for each school is different . also the certification and acknowledgement .

1. ANALYSIS OF SOLUTIONS THAT
HEAT UP WHILE FREEZING AT
ROOM TEMPERETURE

2. index

3. Objective
The purpose of this project is to determine how
and why the solution of water and sodium
acetate freezes the way it does. I will also
investigate why the solution heats up when it
freezes. In order to reach my goals, I will have
to find out how the change from a liquid to a
solid state produces heat.

I also want to find out if it is possible to create
a solution that will produce similar effects,
using vinegar and baking soda.

4. Introduction

This phenomenon also known as “Hot ice”
refers to a popular chemical demonstration in
which a solution of sodium acetate dissolved in
water and placed in a freezer instantly
solidifies when poured from its container or
when a single crystal of solid sodium acetate is
dropped into the solution. The solidification
process releases heat and thus gives the
appearance of the formation of hot ice.
Chemistry instructors use this to demonstrate
the phenomenon of supersaturation, or the
ability of some solutions to contain more
dissolved material than they normally should.

5. Theory
SUPERSATURATION
The phenomenon of supersaturation occurs
when the amount of solute dissolved in a given
amount of solvent exceeds the saturation point.
Scientists do not fully understand the
mechanism by which solutions become
supersaturated. Precipitation requires the
formation of a small solid crystallite in the
solution, a process called “nucleation.” After
the crystallite forms, a second process, known
as growth, enlarges the crystallites to the
macroscopic level such that they can be
observed and isolated. But growth does not
occur without nucleation, and some solutes
under certain conditions resist this process.
Nucleation tends to require a “rough” surface

6. on which to initiate. The rough surface may be
an impurity, such as dust particles, or a scratch
on the inside of the glass container in which
the solution resides. Alternatively, an
experimenter can initiate nucleation
deliberately by adding a single, small crystal of
the compound being precipitated.
Consequently, most instructions for the hot ice
demonstration call for adding a few grains of
solid sodium acetate to the supersaturated
solution to induce crystallization.

SODIUM ACETATE
Sodium acetate is an ionic compound
consisting of sodium cations, Na(+), and
acetate ions, C2H3O2(-). Like most acetates, it
exhibits high solubility in water: 76 g dissolves
in 100 ml at 0 degrees C. The solubility,
however, increases substantially at higher
temperature. The hot ice demonstration calls
for creating a saturated solution of sodium
acetate in hot water, then placing the solution
in a freezer. As the solution cools and
approaches 0 degrees C, the concentration of

7. sodium acetate will remain above 76 g per 100
ml, i.e., the solution will be supersaturated.




HOT ICE
The precipitation of a solid from a solution
results in decrease in the disorder of the
system. That is, in the solution the ions move
freely in random directions and therefore
exhibit high disorder. When the ions combine
to form solid crystallites, their freedom of
motion becomes restricted. Scientists describe
this as a decrease in the entropy, or disorder, of
the system. The laws of thermodynamics
stipulate that for a process exhibiting a
decrease in entropy to occur spontaneously,
such as the precipitation of a solid from a
solution, the process must also liberate heat.
Consequently, the introduction of a solid
crystallite of sodium acetate will warm itself as
the sodium acetate precipitates from solution.

8. Materials
 Sodium acetate - NaC2H3O2
 Vinegar - CH3COOH
 Baking soda - NaHCO3
 Water
 Electric stove
 Beaker
 Stir stick
 Thermometer

9. Procedure
1.Begin by putting the sodium acetate into a
pan.
2.Add a small amount water to the sodium
acetate.
3.Heat the mixture on a stove until the sodium
acetate has dissolved.
4.Pour the solution into a container.
5.Do not pour in any undissolved crystals.
6.Put the container into the freezer or
refrigerator for a while.
7.When the solution cools down to room
temperature, take it out.

10. 8.Repeat this procedure for other proportions
of sodium acetate and water.
9.Pour the water on a surface and note the
results.
10.Repeat the above steps after making
solutions of baking soda and vinegar.
Observation
S.NO Amount of
sodium acetate(g)
Amount of
water (g)
Change in
temperature (
of)
1 80 100 40
2 90 110 40
3 100 120 40
4 100 110 40
Relative change in temperature for respective
supersaturated solution of sodium acetate
available in lab.

S.NO Amount of
sodium acetate(g)
Amount of
water (g)
Change in
temperature (
o
f)
1 80 100 40
2 90 110 40

11. 3 100 120 40
4 100 110 40
Relative change in temperature for respective
supersaturated solution of baking soda and
vinegar

Results
All of the solutions produced the same effects,
increasing about 40 degrees Fahrenheit in
temperature.
The solutions of vinegar and baking soda
behaved exactly like the solutions of sodium
acetate and water.
As soon as I introduced a tiny amount of
sodium acetate to the solutions, the solution
began to freeze outwards from where the
sodium acetate came into contact with the
surface of the liquid.
In a few seconds the entire solution was frozen
and had noticeably become warmer.

12. Conclusion
The solutions I made of sodium acetate and
water were all supersaturated and supercooled.
This made each solution very unstable. The
sodium acetate also raised the temperature of
the water from room temperature to about 110
degrees Fahrenheit.

I concluded that when the solutions freeze, an
exothermic process takes place in which heat is
given off. The solution has to heat up in order
to reach its freezing temperature and as it is
freezing, it releases energy, which causes it to
feel warm.

13. This project is to find out how and why the
solution of sodium acetate freezes the way it
does and why it significantly warms up when it
does freeze.


Bibliography
 Journal of Chemical Education:
Crystallization of Supersaturated
Sodium Acetate.
 Elmhurst College: Introduction to
Ionic Compounds.
 Oklahoma State University: Solutions
 Washington University in St. Louis:
Mineral Nucleation and Growth.
 Mallinckrodt Baker, Inc.: Material
Safety Data Sheet - Sodium Acetate.