Tiny Bubbles Lab

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Hydrogen Peroxide in the Presence of Yeast

Abstract
A number of different variables, such as the concentration of the hydrogen peroxide solution or the temperature at which the reaction occurs, can affect the rate at which yeast breaks down hydrogen peroxide. To prove this we first tested the solution with 3% concentration of peroxide, the paper that was soaked in yeast rose in 1.7 seconds. After that we changed our concentration to 2.25%, 1.5%, and .75% of hydrogen peroxide to see the effects it had on the amount of time it took the felt to completely drop and rise. On 2.25% it took 2.8 seconds, 1.5% took 3.2 seconds, and .75% took 3.9 seconds.

Introduction
When yeast and hydrogen peroxide react, the peroxide decomposes into water and oxygen gas causing bubbles to form. These bubbles cause the felt to rise.

Problem
In this experiment we measured how long it took for the piece of felt soaked in a yeast solution to sink and rise in the test tube. The amount of time it takes for the felt to sink and rise indicates how oxygen bubbles are formed, as hydrogen peroxide is broken down.

Hypothesis
The amount of hydrogen peroxide directly influences the amount of time it takes to break down the yeast resulting in “tiny bubbles”, and the felt to rise to the top of the test tube.

Procedure
Supplies:
▪ Hydrogen Peroxide
▪ Yeast suspension
▪ 4 felt disks
▪ 5 test tubes
▪ Clock
▪ Forceps
▪ 5 paper cups
▪ Graduated cylinder

Results
See Graph on Lab Sheet

Analysis and Conclusion-
For this experiment our dependent variable was the paper with yeast on it, and our independent variable was the concentration of Hydrogen Peroxide we put in each solution. We tested the amount of time it took for the peroxide to break down yeast at 3%, 2.25%, 1.5%, .75% and 0% concentration. The fastest reaction time was 1.7 at 3% concentration....
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