A chemical
report can be made after we have done a simple experiment or in a
laboratory, following an experimental sample performed in a chemical
laboratory.
1. OBJECTIVES OF EXPERIMENT
-
Observe the effect of temperature change on reaction rate
2. LITERATURE REVIEW
2.1
Theoretical Basis
Chemical
Kinetics is the assessment of the rate and mechanism of chemical reactions. Iron
rusts faster in moist air than in dry air, eating more quickly decomposes when
not cooled. This
is a typical example of complex chemical changes with varying rates according
to reaction conditions (Sunarya, 2002).
Reaction Rate
The
reaction rate of a chemical reaction is a measure of how the concentration or
pressure of the substances involved in the reaction changes with time. Reaction
rate analysis is very important and has many uses, for example in chemical
engineering and chemical equilibrium studies. The reaction
rate is fundamentally dependent on:
•
Reactant concentrations, which usually make the reaction run faster when
concentration is increased. This
is due to increased atomic impact per unit time,
•
Surface area available for reactants to interact, especially solid reactants in
heterogeneous systems. Large
surface area will increase the reaction rate.
•
Pressure, by increasing pressure, we decrease the volume between molecules so
that it will increase the collision frequency of the molecule.
•
Activation energy, which is defined as the amount of energy required to make
the reaction start and run spontaneously. The
higher activation energy implies that the reactants need more energy to
initiate the reaction than the lower activation energies.
•
Temperature, which increases the reaction rate when raised, this is because
high temperatures increase the molecular energy, thus increasing collisions
between molecules per unit time.
• The presence or
absence of a catalyst. The
catalyst is a substance that alters the path (mechanism) of a reaction and
increases the reaction rate by decreasing the activation energy required for
the reaction to proceed. The
catalyst is not consumed or altered during the reaction, so it can be reused.
•
For some reactions, the presence of electromagnetic radiation, primarily the
vitiligo, is required to break the bonds necessary for the reaction to begin. This
mainly occurs in reactions involving radicals (Sukamto, 1989).
The
rate of reaction is related to the concentration of the substances involved in
the reaction. This
relationship is determined by the rate equations of each reaction. It should be noted that some
reactions It should be noted that some reactions have a speed
independent of reaction concentration. This is called a zero-order
reaction. Reaction
kinetics is a branch of chemistry that deals with reaction rates and the
factors that influence them. The
rate or rate of the reaction is the change in the concentration of reagents or
products in a unit of time. The
rate of a reaction can be expressed as the rate of reduced concentration of a
reactant, or the rate of increase in the concentration of a product. The concentration
is usually expressed in moles per liter. The
reaction rate of a chemical reaction can be expressed by the rate equation of
the reaction. For the
following reactions:
A + B → AB
The
reaction rate equation is generally written as follows:
R = k [A] m [B] n
K
as the reaction rate constant, m and n are the partial order of each reactant.
The
magnitude of the reaction rate is influenced by the following factors:
1. The nature
and size of reagents
2. Concentrations
of reagents
3. The reaction temperature
4. Catalyst
(Sukamto, 1989).
Nature and Size of
Reagents
The
reagents properties and reagent size determine the rate of reaction. The
more relative the reactant nature of the reaction rate will increase or the
reaction progresses faster. The
more the surface area of the reaction rate reactants will increase, this is
explained by the increasing surface area of the reacting agent, the
interaction of the reactant agent is wider. The
surface of the reagents can be expanded by reducing the size of the reagents. Thus,
to increase the rate of reaction, the reactant agent in powder form is
preferable when compared in the form of chunks.
The nature of reagents. Substances
differ significantly in their rate of chemical change. The
hydrogen and flour molecules react violently, even at room temperature, by
producing hydrogen fluoride molecules.
H2
+ F2 → 2HF (very fast at room temperature)
In
similar circumstances, the hydrogen and oxygen molecules react so slowly that
no chemical change occurs:
2H2 + O2 → H2O
(Sunarya, 2002).
Concentrations of reagents
In
general, if the greater the concentration of the substance the reaction rate is
greater, and vice versa if the concentration also, and vice versa if the
sentence of a substance the smaller the reaction rate becomes smaller. For some
reactions, the reaction rate is getting smaller. For
some reactions, the rate of reaction can be expressed by a mathematical
equation known as the reaction rate or reaction law called the order of the
reaction. Determining
the order of reactions of a chemical reaction in principle determines how much
influence the change in reagent concentration to the reaction rate (Keenan,
1979).
Temperature or
Temperature Reaction
The rate
of a chemical reaction increases with increasing temperature. Usually
an increase of 10ºC will tuck two or three rates of a reaction between the
molecules. The
increase in the rate of this reaction can be explained in part as the faster
the molecules move around at higher temperatures and hence collide with each other
more often. However,
this has not been explained entirely, to more often colliding molecules, but
they also collide with greater impact (impact), as they move faster. At
large temperatures, as more molecules have greater speed and hence have enough
energy to react.
Almost
all reactions become faster when the temperature is increased because the given
heat will increase the kinetic energy of the particles of the interaction. As
a result the number and energy of the collision increase (Sunarya, 2002).
Catalyst
The
catalyst is a substance added to a reaction to speed up the course of the
reaction. The
catalyst usually reacts temporarily and then re-forms as a free agent. A
reaction using a catalyst is called a catalyst reaction or a process called
catalyst.
Properties of the catalyst:
1.
The catalyst does not react permanently, since it does not undergo chemical
changes during the reaction.
2.
The catalyst does not affect the reaction end result.
3.
The catalyst does not start the reaction but only affects its speed.
4.
The catalyst works effectively at the optimum temperature.
5.
A catalyst affects only the specific reaction rate, meaning the catalyst acts
on one reaction or a kind of reaction and not for other types of reactions.
6.
The activation of the catalyst may be enlarged by another substance called
promoter.
7.
The result of a reaction can sometimes act as a catalyst and is called an
autocatalyst.
8.
The catalyst may react with other substances so that the catalyst properties
are lost.
9.
A catalyst that can slow down the reaction is called a negative catalyst
(Sunarya, 2002).
Catalyst Classification:
Based
on the phase can be divided into 2, namely homogeneous catalyst and
heterogeneous catalyst.
1.
Homogeneous catalyst is a catalyst which has the same phase as the reagent,
possibly gas, liquid and solid.
2.
Heterogeneous catalysts are catalysts having different phases with reagents. Generally
these catalyst substances are solid and liquid or gas reactants (Sunarya, 2002).
3. METHOD OF EXPERIMENT
3.1 Tools and Materials
3.1.1 Tools
- 6 Test tubes
- Drop pipette
- Stopwatch
- 3 cup goblets
- Bunsen
3.1.2 Materials
- 2 ml of 0.1 M oxalic
acid
- 0.5 ml of H2SO4 6 M
- KMnO4 0.1 M
3.2 Work Scheme
3.2.1. The influence of
temperature on the reaction rate
For
this experiment, there is an example of a reaction between oxalic acid and
potassium permanganate in an acidic atmosphere
1.
take 6 test tubes, fill each with 2 ml of 0.1 M oxalic acid and 0.5 ml of 6 M
sulfuric acid.
2.
Prepare 3 cups of trophy, fill half with water. The
first cup of the cup was boiled, the 2nd cup cup was heated to 50 ° C, and the
third cup was not heated.
3.
Insert 2 test tubes into each cup. After
10 minutes, into each tube plus 3 drops of KMnO4 0.1 M. notice the color change
and record the time and reaction in each tube.
4. RESULT AND DISCUSSION
4.1. Results
From
the experiment conducted got the following results:
|
repeated
|
temperatures
|
|
100
|
50
|
25
|
|
1
|
purple 0 s
brown 10 s
Bening 13 s
|
purple 0 detik
brown 17 detik
Bening 22 detik
|
purple 0 detik
purple young 17 detik
brown 34 detik
Bening 51 detik
|
|
2
|
old
|
old
|
old
|
|
averages
|
7,67 s
|
13 s
|
25,5 s
|
4.2. Discussion
So
based on the experiment can be seen the color changes that occur and how many
seconds the reaction rate of the experiment. The
higher the temperature the faster the reaction rate progresses.
5. REFERENCES
Keenan, et al. 1979. Chemistry for Universities. Jakarta: Erland.
Sukamto. 1989.
Chemical Physics. Jakarta:
PT.Bhineka Cipta.
Sunarya, Yayan. 2002.
Basic Chemistry II Based on Recent Chemical Principles. Bandung: Alkemi Grafisindo
Press.
6. APPENDIX
