Unit 1: Becoming a Scientist
Introduction
The purpose of Unit 1 was for us to learn how to become scientists by learning the ins and outs of how an experiment works, our ultimate goal was making our own experiment. Performing multiple experiments before creating our own, we observed the format in which the experiments were written, how the calculations worked, and how to use the experiment to reach a conclusion. My partner, Amelia, and I devised a lab that answers the question: “Which brand of regular tampon absorbs the most liquid?”. We made a list of our materials needed, created a list of direct instructions, then performed our experiment—keeping track of our data in our lab notebooks. The knowledge we have of how labs work was enough for us to carry out our own experiment, and we learned each different component of the lab in different sections.
Process
At the beginning of the year, we were given a set of goals to reach and questions to answer and different ways to complete each of them. One very important skill we learned was lab safety. We learned this by watching an demonstration of proper lab safety, reading our lab manuals, and taking a test that would earn us our lab certificates. Proper lab behavior/safety was one of the first things we learned because it is important—and required—to perform any lab well. After this, we learned how to write the purpose of an experiment, create proper charts, and correctly record calculations.
Calculations are a very important step in an experiment. We learned how to calculate the reliability of our experiments by measuring their percent variation and percent error. Percent variation determines the precision, or reproducibility, of the information. The formula is: the range of data divided by the average, multiplied by 100 to find the percentage. Because we are not in a very high tech lab, data with a percent variation of about 15% or lower is regarded as reliable, as the tools being used may not be the most exact. Percent error determines how accurate, or how close to the accepted value, your data are. The formula for percent error is: what you measured subtracted by the standard accepted value, divided by the standard accepted value and multiplied by 100 to get the percent. As shown in Table 3 of my lab report, Amelia and I got better at collecting more reliable data as we performed our experiment. Another math component that is very important, other than calculations, is significant figures—or ‘sig figs’. Sig figs are what they sound like: the ‘important’ numbers used in a number. It is important to use sig figs in Chemistry because they can greatly affect the reliability of your data. For example, the number 2 has one sig fig (the two) but the number 2.0 has two sig figs, because the person that reached this number knows that it is exactly 2.0, not just 2. The third math equation we learned was percent composition: mass of part divided by total mass. This is important to use because it is another way to test the reliability of your results. When we did the ‘Separating a Mixture’ lab, we had to find the percent composition of three different materials: iron, sand, and salt. In the end, the three percents should add up to 100%, and we will be able to see if our data were correct.
Lastly, we needed to be able to analyze the data of our experiment directly. This means that the conclusions we draw from our experiment have to be based on the data we collected and background research (if needed). This was a skill that we learned as we performed our experiment. When writing the conclusions for my lab report, I would not have been able to say that Tampax tampons and Playtex sport tampons are more reliable than Equate tampons because they cost more. Although price typically coincides with the quality of the product, it would not be up to me to use that, as it does not relate to my experiment. Instead, I compared the averages of the water held by each brand and recognized that the Playtex sport tampons were the most reliable, and I did not mention qualitative observations–such as if the tampon were damp or if it fully expanded–in this statement.
Lighting the Bunsen burner, part of the Lab Safety test.
Matilda and me holding our lab certificates.
Dropping purple-dyed water onto a tampon for my 'Truth in Advertising' lab.
Product
Amelia and I ended up with the amount of water that can be absorbed by the different brands of tampons in grams/mililiters. We dripped water taken from a 20mL filled beaker onto the tampon placed in a funnel and stopped when we saw any water leak through. We recorded the mass of the tampon and funnel without any water and then recorded the mass of the tampon and funnel after a certain amount of water was dripped on it. In our calculations, we subtracted the dry mass from the wet mass to get the amount of water that the tampon sufficiently held.
Reflection
Overall, this unit taught me to take a second to ponder a slogan on a chip bag or a headline and to question where the creator got their information from. While learning about accuracy and precision, I saw that it is very likely for a mistake to be made while performing an experiment, and facts are based on the conclusion of experiments. Behind all of those experiments are scientists and their data may lead to many different conclusions. For instance, it has been advertised that regular tampons can hold six to nine grams of liquid and this conclusion was reached by performing the ‘syngina test’. This appears to be a reliable way to test the absorbency of tampons, and I trust their conclusions, but before I had really looked into this test I had never trusted the absorbency level labels or question how those numbers came to be.
The most trouble I had in this unit was being able to communicate my ideas/conclusions. When doing background research for our final experiment, I was retaining a lot of different pieces of information. While writing the lab report, I would sometimes forget that I am supposed to be explaining everything, even if it might be ‘common knowledge’. I did enjoy and improve in my ability to collect data while performing an experiment, though I hit a couple of rough patches and spent a lot of time setting up tables.
This unit has made me feel much more comfortable in a lab and confident in my ability to safely use different tools, follow instruction, and adapt to fix any problems that may arise. For future experiments, I will now more efficiently complete labs and draw conclusions based off of the data collected and calculations made.