Name:Seung Hee ShinYeast Experiment

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 SugarI will change it by measuring 5g of sugar and 10g of sugar to use electronic scale.

Output variable: The Amount Of Carbon DioxideI will measure by finding the difference between before and after 10 minutes.

Control variables:

Control variable 1: The Amount Of WaterI will keep it the same by measuring 100ml of water to use measuring cylinder.

Control variable 2: The Amount Of YeastI will keep it same by measuring 4g of yeast to use electronic scale.

Control variable 3: The Temperature Of The WaterI 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 beaker2-Measuring Cylinder-24g of yeast-45g of sugar-300ml of water-Stop watch

Diagram:

Method:

Set the equipment as I wrote before.

Put a piece of tissue on an electronic scale.

Measure 4g of yeast

Put it in a beaker(250ml triangle shaped beaker)

Put a piece of tissue on an electronic scale

Measure 5g of sugar

Put it in a beaker

Measure 100ml to use measuring cylinder

Put 100ml of water in the beaker

Mix the mixture(yeast+sugar+water)

Wait for 10 minutes

Write down the result

Repeat step from 2 to 5

Measure 10g of sugar

Repeat step from 7 to 12

Put the equipment back

Clean the table

Data TableData 1 : Difference between before and after 10 minutes, the first experimentTrialThe amount of sugar(g)Difference between before and after 10 minutes(g)

150.02

2100.12

Data 2 : Difference between before and after 10 minutes, the second experimentTrialThe amount of sugar(g)Difference between before and after 10 minutes(g)

150.02

2100.02

Data 3 : Difference between before and after 10 minutes, the third experimentTrialThe amount of sugar(g)Difference between before and after 10 minutes(g)

150.15

2100.21

Averages : Difference in weight after 10 minutes(g)

The amount of sugar(g)Trial 1Trial 2Trial 3Average

50.020.020.150.06

100.120.020.210.12

GraphGraph : The Yeast ExperimentConclusion:

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.