1) The document describes an experiment to test how the amount of yeast and sugar affects the amount of carbon dioxide released. 2) The experiment varied the amount of sugar (5g and 10g) while keeping the amount of yeast and water constant. The difference in weight before and after 10 minutes was measured. 3) The results showed that with more sugar (10g), the weight decreased more after 10 minutes, indicating more carbon dioxide was released. However, one trial was unreliable due to a problem maintaining the water temperature.

1. Name:Seung Hee Shin
Yeast Experiment

2. Name: Seung Hee Shin
Group Members: Jung Min Kim, Tony
Date of experiment: 10/20~22/Wed~Fri(2010)
Lab Report Of The Yeast Experiment
Aim: The purpose of this experiment is to see how the amount of yeast can affect the amount of
Carbon Dioxide released.
Hypothesis: If the amount of sugar increases, then the weight due to the Carbon Dioxide emission
will be lighter. Yeast needs energy to grow. Sugar supplies energy to the yeast. Therefore, yeast uses
energy from the sugar, this process is called 'respiration'. In result, the more sugar there is, the more
active the yeast will be and faster its growth.
Variables:
Input variable: The Amount Of Sugar
I will change it by measuring 5g of sugar and 10g of sugar to use electronic scale.
Output variable: The Amount Of Carbon Dioxide
I will measure by finding the difference between before and after 10 minutes.
Control variables:
Control variable 1: The Amount Of Water
I will keep it the same by measuring 100ml of water to use measuring cylinder.
Control variable 2: The Amount Of Yeast
I will keep it same by measuring 4g of yeast to use electronic scale.
Control variable 3: The Temperature Of The Water
I will keep it the same by using the water in the machine that can keep the
temperature of the water to 40℃.
Materials:
-Electronic Scale
-A piece of tissue
-250ml triangle shaped beaker☓2
-Measuring Cylinder
-24g of yeast
-45g of sugar
-300ml of water
-Stop watch

3. Diagram:
사진
Method:
1. Set the equipment as I wrote before.
2. Put a piece of tissue on an electronic scale.
3. Measure 4g of yeast
4. Put it in a beaker(250ml triangle shaped beaker)
5. Put a piece of tissue on an electronic scale
6. Measure 5g of sugar
7. Put it in a beaker
8. Measure 100ml to use measuring cylinder
9. Put 100ml of water in the beaker
10. Mix the mixture(yeast+sugar+water)
11. Wait for 10 minutes
12. Write down the result
13. Repeat step from 2 to 5
14. Measure 10g of sugar
15. Repeat step from 7 to 12
16. Put the equipment back
17. Clean the table
Data Table
Data 1 : Difference between before and after 10 minutes, the first experiment
Trial The amount of sugar(g) Difference between before and after 10 minutes(g)
1 5 0.02
2 10 0.12
Data 2 : Difference between before and after 10 minutes, the second experiment
Trial The amount of sugar(g) Difference between before and after 10 minutes(g)
1 5 0.02
2 10 0.02

4. Data 3 : Difference between before and after 10 minutes, the third experiment
Trial The amount of sugar(g) Difference between before and after 10 minutes(g)
1 5 0.15
2 10 0.21
Averages :
Difference in weight after 10 minutes(g)
The amount of sugar(g) Trial 1 Trial 2 Trial 3 Average
5 0.02 0.02 0.15 0.06
10 0.12 0.02 0.21 0.12
Graph
Graph : The Yeast Experiment

5. Conclusion:
From this experiment, I could find when the amount of the sugar increases, the weight of the
mixture goes down. This is because the yeast can get energy and grow fast when the amount of the
sugar increases. As a result, the Carbon Dioxide is released more. As you see in data table and the
graph, the second experiment went wrong. However, I can still see the relationship between the
amount of the sugar and the amount of Carbon Dioxide. To worked these out, I changed the amount
of sugar to 5g and 10g. I could found very big difference between the weight of before and after 10
minutes. The second experiment went wrong because of our mistake, so the second experiment is
not reliable. However, the first experiment and the third experiment went very good. They are
reliable. The amount of the water was very difficult to measure. Even though Tony measured
accurately to use the measuring cylinder, the weight of the mixtures were different. For example, we
got 201.16g for the mixture with 5g of sugar. Then the weight of the mixture with 10g of sugar has
to be 206.16g. However, the weight was 208.27g. Anyway, I could still see the pattern. The
hypothesis was correct, the more put sugar, the more carbon dioxide released.
Evaluation:
The second experiment is not reliable. This is because we forgot to put the bottle of water back to
the machine which can control the temperature of the water. We kept it for the 10 minutes and then
used it to put the water into a beaker with 10g of sugar. The temperature of the water affects the
amount of the Carbon Dioxide. When the more temperature goes down, the less active the yeast will
be. Also, if the temperature of the water extremely goes up, like 70℃, the yeast would be dead. So
we had to put the bottle of the water back or get a new bottle of the water. So the result of the
difference in wight after 10 minutes of the mixtures with 5g and 10g of sugar were same. The
method is reliable. I could get these great results because I followed the method exactly except for
this; turning on the power of the electronic scale and get a bottle of the water. Except for them, the
method is very reliable. In result, the method has to be more specific. If I were to continue the
investigations, I could find other reasons which can affect the amount of Carbon Dioxide and why.
Also, If I can do the experiment again, I would do 4 trials. That is because we did only 2 trials.