The results shown in table 1 clearly show that when the volume of yeast is increased in the milk solution, so does the rate of oxygen depletion and therefore the rate of eutrophication. It shows that when 2mL of yeast solution was added it took 32.86 minutes on average for the milk to be depleted of oxygen, while it took only 7.46 minutes on average for the 10mL of yeast to use up the oxygen present.
Figure 1 shows the minimum, maximum and average length of time it took for each solution to be depleted of oxygen. The scatter in the values suggests the presence of random errors.
This is representative of how eutrophication works in an aquatic environment. It shows that the greater the number of blue-green algae then the faster the oxygen depletion
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A random error is caused by any factor which randomly affects the amount of scatter in the data. An increase in sample size allows averages to be calculated which reduces the effects of these random errors. By removing outliers in the data, the effect of random errors can be further minimised. A large amount of scatter in results indicated low precision and a large number of random errors. Some possible random errors in this experiment may have arisen when measuring the 12mL of milk solution for each test tube; some may have had slightly more and others slightly less than 12mL. Another random error could have occurred when adding 4 drops of methylene blue, some drops may have contained more liquid than others, meaning some test tubes may have contained less methylene blue indicator than …show more content…
By taking a sample size of 5, while still not particularly large it decreased the effect of random errors as an average was able to be calculated. Another strength was using the same size test tubes throughout the experiment. This made sure the surface area and exposure to oxygen in the air was kept consistent which would allow for more accurate results. A weakness of this experiment was that it was difficult to distinguish the exact point when the methylene blue had disappeared. As the top part of the test tube was exposed to oxygen in the air, the milk solution never went completely white and there was a blue ring on top of each test tube which stayed blue. It was also difficult to put the exact same amount of methylene blue into each test tube because you are not actually measuring it but rather just placing drops into the test tubes which is a little difficult to
3. The time taken for the yeast to heat up to the temperature of the
This means that there are more collisions between the solid and liquid. Amount of tap water H2O used, i.e. volume (in ml) of the syringe. Amount of Alka-Seltzer tablets used, i.e. quantity of the tablets. one is used for the. Number of times the solution is stirred.
= I predict that if the concentration is high in the yeast then the speed of oxygen produced in the reaction with hydrogen peroxide will also be high. This is because the amount of yeast that can react with the hydrogen peroxide can get no higher and will have the maximum affect on the reaction. If the concentration is more in favour of water then the amount of oxygen produced will be slow because there is not as much yeast to react with the hydrogen peroxide, giving less oxygen. If the temperature is not in favour of the limits to the yeast then the amount of oxygen produced will be small because the enzyme will have denatured. If the temperature is in favour of the yeast then the amount of oxygen produced will be high because it is at the prime temperature for the yeast to react.
Going into details of the article, I realized that the necessary information needed to evaluate the experimental procedures were not included. However, when conducting an experiment, the independent and dependent variable are to be studied before giving a final conclusion.
The experiment is aimed at giving a better understatement of osmosis process and the different conditions in which osmosis occurs.
Planning Firstly here is a list of equipment I used. Boiling tubes Weighing scales Knife Paper towels 100% solution 0% solution (distilled water) measuring beakers potato chips Cork borer. We planned to start our experiment by doing some preliminary work. We planned to set up our experiment in the following way.
We were not given any instructions either to shake or not to shake the test tubes with the coloured solutions before inserting them in the spectrophotometer to read the absorbance. By shaking each test tube a certain number of times before putting it in the spectrophotometer could have improved the accuracy of the of absorbance of the solutions.
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
This would give us an extra measure of accuracy each time. Another way to improve the experiment and to produce consistent readings was to used distilled water. This is because the distilled water contains no impurities and therefore no hardness in water.
Investigating the Effect of Temperature on the Fermentation of Yeast To fully investigate the effect of temperature on the rate of fermentation of yeast Background Information Yeast is a single-cell fungus, occurring in the soil and on plants, commonly used in the baking and alcohol industries. Every living thing requires energy to survive and through respiration, glucose is converted into energy. There are two types of respiration available to living cells are: 1.
Overall I think I carried out the experiment in a precise way and I took my time trying to make all my measurements as accurate as possible so that my data is reliable. Next time I will do more tests instead of just 3 so I have more results and so I could get a more accurate average. I will also do the experiment with more fruit juices to see if there are other fruits with a higher content of vitamin C. I will do an experiment to see if there is a difference in Vitamin C levels between fresh juice and store bought juice. I can also test different brands of juice to see if they have different levels of vitamin C.
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.
Possible sources of error in this experiment include the inaccuracy of measurements, as correct measurements are vital for the experiment.
There were five test solutions used in this experiment, water being the control, which were mixed with a yeast solution to cause fermentation. A 1ml pipetman was used to measure 1 ml of each of the test solutions and placed them in separated test tubes. The 1 ml pipetman was then used to take 1ml of the yeast solution, and placed 1ml of yeast into the five test tubes all containing 1 ml of the test solutions. A 1ml graduated pipette was placed separately in each of the test tubes and extracted 1ml of the solutions into it. Once the mixture was in the pipette, someone from the group placed a piece of parafilm securely on the open end of the pipette and upon completion removed the top part of the graduated pipette.
Eutrophication is “the process by which a body of water acquires a high concentration of nutrients, especially phosphates and nitrates. These typically promote excessive growth of algae. As the algae die and decompose, high levels of organic matter and the decomposing organisms deplete the water available oxygen, cause the death of other organisms, such as fish. Eutrophication is a natu...