Identify the Independent Variable, Dependent Variable , Control and Constants? Essay

Published: 2020-04-22 08:25:56
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Category: Hydrogen

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Catalases Reaction with Hydrogen Peroxide When pH Level is ChangedAll living organisms contain catalysts. These catalysts are used to speed up reactions and processes in all organisms. Enzymes are responsible for enabling chemical reactions that occur in all living things. In this experiment the enzyme catalase (found in potatoes) and hydrogen peroxide cause chemical reactions to occur more quickly within living things. This happens because enzymes are acting as catalysts. Using a potato and hydrogen peroxide, observations can be made on how enzymes like catalase break down other substances. The decomposition of hydrogen peroxide into water and oxygen is sped up by the catalase. In the experiment, it was hypothesized that the reaction would slow significantly at pHs of 6 and 8since they are not within the normal pH range of a cell. This hypothesis was proven wrong since pH 6 had the most foamy top, having a bigger and faster reaction.

Some of the independent variables in this experiment were pH level and time. The dependent variable in this experiment is the pressure of the oxygen after the catalase reacted with the peroxide.
Controlled Variables Method of Control
Size of test tube Used same sized test tube for the whole experiment
The volume of hydrogen peroxide Used 7mL of hydrogen peroxide
Temperature All experiments were held in the same room
Procedure Used same methods and steps every time

Potato Core
Hydrogen Peroxide
Test Tube
Test Tube Rack
Razor Blade
Manila Folder

Place potato core in the test tube
Have the timer for 90 seconds ready
Add 7mL of hydrogen peroxide.
Measure the height of bubbles from reaction after 90 seconds.
Record any other qualitative data.
Repeat for a total of 5 trials.
Throw away potato cores after each use. Pour Hydrogen peroxide down the drain.
Clean lab equipment when complete.
Safety Notes:
Caution was used when cutting the potato core into 1.5 cm pieces with the razor blade.

Qualitative Data:
Some of the observations consisted of small fizzy bubbles, off-white foam top, and the potato starting to brown and even becoming softer. These reactions were seen in some form through all the different pHs. Some potatoes floated to the top of the hydrogen peroxide due to bigger bubbles forming underneath the potato.
Quantitative Data:
4th Trial 1 (cm) Trial 2 (cm) Trial 3 (cm) Trial 4 (cm) Trial 5 (cm) Average Standard Deviation
Water 0.20 0.18 0.15 0.17 0.19 0.18 0.02
pH 4 0.00 0.00 0.00 0.00 0.00 0.00 0.00
pH 5 0.10 0.10 0.10 0.10 0.10 0.10 0.00
pH 6 0.20 0.20 0.20 0.30 0.20 0.22 0.04
pH 7 0.00 0.00 0.00 0.00 0.50 0.10 0.22
pH 8 0.20 0.10 0.15 0.10 0.10 0.13 0.04
pH 9 0.20 0.20 0.00 0.10 0.20 0.14 0.09
pH 10 0.10 0.10 0.10 0.12 0.10 0.10 0.01
Errors and Uncertainties:
Processed Data and Calculations:

The graph above shows the average of the 5 trails in each pH level. The graph shows pH 6 to have the highest average of foamy top, this means pH 6 had the fastest and biggest reaction with the hydrogen peroxide.
Catalase acts as the catalyzing enzyme in the decomposition of hydrogen peroxide. Nearly all living things possess catalase. This enzyme aids in the decomposition of one substance into another. Catalase decomposes hydrogen peroxide into water and oxygen.
Williams, J. (1928, March 20). THE DECOMPOSITION OF HYDROGEN PEROXIDE BY LIVER CATALASE. Retrieved December 15, 2017, from to Enzymes. (n.d.). Retrieved December 15, 2017, from (n.d.). Retrieved December 15, 2017, from

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