Yeast Beasts In Action Lab Investigation

Introduction


Yeasts are microorganisms. They can break hydrogen peroxide down into water and oxygen gas. In this experiment you will investigate yeast activity in acidic, neutral, and basic mixtures. You will observe yeast activity by measuring pressure caused by the oxygen gas they produce.


Problem


How does yeast activity differ in acidic, neutral, and basic mixtures?


Hypothesis


The yeast activity in the acidic mixture will be the greatest because the more acidic something is, the greater reaction will take place.


Results


The acidic mixture was a diet soft drink, and the highest kPa was 118.62 kPa. The neutral mixture was skim milk, and the highest kPa was 111.97 kPa. The basic mixture was stomach antacid, and the highest kPa was 124.04 kPa. 


Conclusion


The yeast activity was the greatest in the neutral (skim milk). It raised the most and it took the longest to stop rising. In fact, it was still rising when the lab was over. I think the reason for this is because of the milk. The milk could have had some chemical in it we didn't know about, or it could have had the greatest reaction because it was skim and not regular milk. The yeast activity was the least in the acidic (diet Coke). It rose the least and it stopped rising after only a few seconds. I think if the soda wasn't diet, or if it was a different kind of soda, the reaction may have been different. However, the stomach antacid had the highest kPa, and the skim milk had the lowest. My hypothesis was incorrect; I thought that the diet soft drink would have the highest kPa, and the stomach antacid would have the lowest. In reality, the Coke's kPa was right in the middle, and the stomach antacid's kPa was the highest.