Lab Report- Chemical Kinetics
Chloe I. Planakis
Department of Chemistry, University of Central Florida, 4000 Central Florida Blvd., Orlando,
FL 32816-2366 (USA)
June 25th, 2021
Introduction
Chemistry background and theory
In this lab, reaction time and rate of reaction is being measured. Reaction rates can be sped up or
changed by a few different methods, such as changing temperature or changing the concentration
of substances within the solution. By changing the temperature, the rate of the reaction will be
changed due to the change in time that the molecules will collide. When the solution is mixed, it
is easy to tell if there is a chemical change taking place. Chemical change can be signified by
change in color, change in temperature, formation of precipitation of rusting, odor production,
and formation of a gas which usually presents as bubbles.
Context and Relevance
This lab is essential for students because it teaches reaction rate and how it can be affected by
different factors like temperature and the amount of concentration of substance in a solution. For
example, if a solution of baking soda and vinegar had more of each substance, the reaction would
have an effect much faster. The data collected in this lab shows that concentration of a substance
can affect the reaction rate, as well as the temperature of the substances when mixed.
Specific Aim
The goal of this experiment is to show the effect of temperature and concentration on reaction
rate of the solution. In this experiment, a mixture of triiodide, thiosulfate, and DI water will be
mixed in a beaker then placed on a stirring plate. After hydrogen peroxide is added, the time it
takes for the solution to change colors will be recorded. The time changing based on trials that
used different temperatures will prove that the temperature of the substances mixed changes the
rate of reaction in solutions.
References
Tro, N. J., Chemistry: A Molecular Approach (New York: Pearson, 2017) p.581
Method Section
Phase 1
During phase one, a question about which actions are able to increase the reaction rate was
asked.
Phase 2
During phase two, a thermometer is first used, and the temperature of the iodide solution is
measured. The temperature is then recorded in the Lab Data. A 10-mL graduated pipet is used,
and 10.0 mL of iodide solution is transferred to the Trial 1 beaker. The exact volume of the
iodide added is recorded into the Lab Data. Then a 1-mL graduated pipet is used, and 1.0 mL of
thiosulfate is transferred into the Trial 1 beaker. The volume of the thiosulfate is recorded into
the Lab Data. A 10-mL graduated pipet is used, and 2.5 mL of DI water is transferred into the
Trial 1 beaker. The volume of the water added is recorded into the Lab Data. A stir bar is added
to the Trial 1 beaker. The Trial 1 beaker is placed on the stir plate, and the stir plate is turned on.
After the stir plate has been mixing, the 10-mL graduated pipet is used, and 7.5 mL of hydrogen
peroxide is transferred to the Trial 1 beaker. The timer is stopped when the reaction has changed
colors, and the time of the reaction along with volume are recorded in the Lab Data. The
observations are recorded in the Lab Data, and the initial concentrations of the reactant are
calculated and recorded in the Lab Data. The rate of reaction for Trial 1 was recorded into the
Lab Data, and the Trial 1 mixture is poured into the “chemicals for disposal” beaker. The used
beaker is placed into the Wash/Waste bin.
Phase 3
For phase 3, steps 1-3 are the same as step 1, though all chemicals are placed into the Trial 2
beaker. As for step 4, 5.9 mL of DI water is transferred by the 10-mL graduated pipet into the
Trial 2 beaker. 5.0 mL of hydrogen peroxide are transferred into the Trial 2 beaker by the 10-mL
graduated pipet, and the when the color changed, the exact time and volumes were recorded into
the Lab Data. After that, the steps following mimic the steps from phase 2, except the Trial 2
beaker was used instead.
Phase 4
For phase 4, all steps from phase 2 were repeated, but the Trial 3 beaker was used, and different
volumes of the solutions were used as well. In this phase, 1.5 mL of DI water were transferred by
the 10-mL graduated pipet, and 8.5 mL of hydrogen peroxide were transferred to the Trial 3
beaker with the 10-mL graduated pipet. All other steps are the same as phase 2 and 3, with only
the beaker used and the volumes of the substances having differed.
Phase 5
For phase 5, the substances are placed in a bucket of ice. The temperature is changed and
recorded into the Lab Data. The steps are still the same as phase 2, but the step to add DI water
to the solution is removed. In this phase, 10.0 mL of hydrogen peroxide are transferred into the
solution and the 10-mL graduated pipet was used. This phase once again uses the Trial 1 beaker.
Phase 6
For phase 6, the substances are left at room temperature, and the temperature of the solutions
were recorded into the Lab Data. Like phase 5, the 10.0 mL of hydrogen peroxide are transferred
into the Trial 2 beaker, and the 10.0 mL graduated pipet was used. In this phase, the Trial 2
beaker was used.
Phase 7
In this phase, the substances are placed onto a heating plate. In this phase, a Trial 3 beaker is also
used. The steps again are the same as phase 5 and 6, with the DI water not being added, and 10
mL of hydrogen peroxide added using the 10 mL graduated pipet.
Phase 8
In this phase the lab has been completed, and all data is available to view.
Results
In this experiment, the rate of reaction was sped up greatly after the substances mixed were
heated.
Data/graphs
Rate of change
Trial 1
0.042
Trial 2
0.028
Trial 3
0.047
Trial 1 (cold water)
0.019
Trial 2 (room
0.055
temperature)
Trial 3 (heated)
0.11
Discussion
The data in this experiment showed the rate of change was sped after the substances were heated,
proving that the temperature of substances did have an affect on the rate of change of the
solution. The different trials included different concentrations of the substances, which also
yielded different results. The results showed that not only does difference in temperature have an
effect on rate of change, but concentration of substances as well.