Analysis of Results
What we were looking for in the experiment results was to find the dish that has the least remaining colonies left. This proves that more bacteria colonies are killed due to the cleaning agent. From the “average” column in the table we filled up earlier, we plotted two graphs that graphed the percentage of colonies compared to the control, and also the raw number of colonies which shows the contrast against the control.
From the graph plotted, the bar with the lowest value is from the cleaning agent Clorox. Clorox has evidently shown consistent effective results for all the trials, while other agents had varying results. Clearly, Clorox is the best bacteria killer amongst all the agents. From the percentage graph, Clorox managed to kill 79.1% of bacteria colonies. In addition, from the other graph that shows the number of remaining colonies, Clorox killed 70.3 colonies, which is the most number of colonies killed compared to the other agents.
According to the effectivity of the agents from best to worst, it would be ranked in this order:
Clorox, LifeBuoy, Mama Lemon, Dettol. With that, our hypothesis was proven wrong, and we came to a new conclusion that Clorox is the most effective cleaning agent. Clorox can be used to clean different areas, to ensure that germs and bacteria are killed, or low levels of them are present to ensure a healthy work or living environment.
*All figures above are calculated through the average and rounded off to 3s.f.
Through the course of the experiment, we discovered that all the agents that were used to conduct the experiment were did not live up to their advertising of removal of 99.9% of germs and bacteria. However, we feel that there might be human error such as the change in the temperature of the environment etc. which have caused our findings to be different.
Explanation of key findings
All the cleaning agents used did not live up to their advertising in which it claimed to have superior cleaning qualities of removing 99.9% of germs and bacteria. Since our hypothesis revolved around Dettol, after the experiment, it is proven that Dettol obviously did not kill 99.9% of bacteria, and did not live up to their reputation despite Dettol being a well trusted brand that is used by many households.
Evaluation of hypothesis
As our hypothesis earlier was “If Dettol is used, it can kill more bacteria than the rest of the agents”, after comparison with the results through the plotted bar graphs, it is evident that Dettol was not the agent that killed most colonies of bacteria, and instead, was the agent that killed the least amount of bacteria. The cleaning agent that killed off the most amount of bacteria was actually Clorox. Thus, our hypothesis is proven to be wrong.
Areas for improvement
Due to a lack of time and resources, we had to reduce the number of trials and repetition of experimental procedures, and we only conducted three trials. To improve our results (to be more reliable), it would be better if we could increase the number of trials.
Also we could have prevented the petri dishes from being contaminated. This would have prevented us from wasting so many resources. We could have worn a mask to prevent contamination from communicating to one another while doing the experiment. Since we were initially unfamiliar with handling the items, we could have improved on handling the items better, so that they would not get contaminated easily
Accuracy & precisionIn our table, the number of colonies present in each dish are accurate to its actual value, since they are in integers. However, the “average” column is calculated to accuracy of 3.s.f. To ensure higher precision of results, the average number of colonies in each trial is taken and used for the graph plotting.