Name: Seung Hee ShinGroup Members: Jung Min Kim, TonyDate of experiment: 10/20~22/Wed~Fri(2010) Lab Report Of The Yeast ExperimentAim: The purpose of this experiment is to see how the amount of yeast can affect the amount ofCarbon Dioxide released.Hypothesis: If the amount of sugar increases, then the weight due to the Carbon Dioxide emissionwill be lighter. Yeast needs energy to grow. Sugar supplies energy to the yeast. Therefore, yeast usesenergy from the sugar, this process is called respiration. In result, the more sugar there is, the moreactive 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 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
Diagram: 사진Method: 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 tableData TableData 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 0.12Data 2 : Difference between before and after 10 minutes, the second experimentTrial The amount of sugar(g) Difference between before and after 10 minutes(g)1 5 0.022 10 0.02
Data 3 : Difference between before and after 10 minutes, the third experimentTrial The amount of sugar(g) Difference between before and after 10 minutes(g)1 5 0.152 10 0.21Averages : 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 0.12GraphGraph : The Yeast Experiment
Conclusion:From this experiment, I could find when the amount of the sugar increases, the weight of themixture goes down. This is because the yeast can get energy and grow fast when the amount of thesugar increases. As a result, the Carbon Dioxide is released more. As you see in data table and thegraph, the second experiment went wrong. However, I can still see the relationship between theamount of the sugar and the amount of Carbon Dioxide. To worked these out, I changed the amountof sugar to 5g and 10g. I could found very big difference between the weight of before and after 10minutes. The second experiment went wrong because of our mistake, so the second experiment isnot reliable. However, the first experiment and the third experiment went very good. They arereliable. The amount of the water was very difficult to measure. Even though Tony measuredaccurately to use the measuring cylinder, the weight of the mixtures were different. For example, wegot 201.16g for the mixture with 5g of sugar. Then the weight of the mixture with 10g of sugar hasto be 206.16g. However, the weight was 208.27g. Anyway, I could still see the pattern. Thehypothesis 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 tothe machine which can control the temperature of the water. We kept it for the 10 minutes and thenused it to put the water into a beaker with 10g of sugar. The temperature of the water affects theamount of the Carbon Dioxide. When the more temperature goes down, the less active the yeast willbe. Also, if the temperature of the water extremely goes up, like 70℃, the yeast would be dead. Sowe had to put the bottle of the water back or get a new bottle of the water. So the result of thedifference in wight after 10 minutes of the mixtures with 5g and 10g of sugar were same. Themethod is reliable. I could get these great results because I followed the method exactly except forthis; turning on the power of the electronic scale and get a bottle of the water. Except for them, themethod is very reliable. In result, the method has to be more specific. If I were to continue theinvestigations, 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.