Recently, I had a lab in our Biology honors class about pH. In the class we are learning about biochemistry and amino acids, hydroxyl groups etc. In this blog lap report, I will explain the lab and break down all the data.
Below are the materials we used for the lab:
In this lab, I used a pH indicator to measure the pH of cabbage juice with a solution added to it. A pH indicator is just a chemical or liquid or substance that changes color when it is exposed to acid or bases. Red cabbage juice contains anthocyanin which changes color depending on the pH. At a pH of 7 which is neither acidic or basic the color of anthocyanin is purple. As you add drops from an acid solution the pH decreases and when you add drops from a base solution it increases. We used an app on our phones called sparkview, and a pH probe to find the actual pH of the solution and associate it with the color. At the very end of the experiment we had 7 tubes that ranged in pH from 4-10 (ours was from 3.5 – 9.1 because the pH started out lower than expected). Our class did this experiment because it would teach us about pH and allow us to start using calculations in Biology. Even though this was only our second lab in Biology so far, we learned a lot about pH. We had to go through safety instructions so the acids would not harm us(we wore “aprons” and goggles). This experiment also allowed us to segway into calculations with moles and molecules. Up till the the start of my 9th grade year, I had no idea what a mole was, but now I know how valuable it is to chemistry. Using the value of a mole we can figure out the amount of molecules or atoms in a solution which is very useful for a scientist. We learned how to find out how many hydrogen ions and hydroxide ions were in the solution and we set up an equation to figure it out. To sum up, our pH lab helped us all learn more about pH and data analysis and allowed us to calculate important data for the experiment.
This is the pH spectrum our group made. It ranged from 3.5 – 9.1
This is a formula a typed up for calculating the amount of hydrogen ions in a solution. Just to specify, the 5 ml is the size of the solution.
Below is data that we analyzed from our experiment.
In this paragraph, I will analyze data from my graphs, pictures and tables.
In my first picture I included the pH spectrum that our group created. We transferred our solution, from a beaker to a test tube for a better and more efficient experience. We used a test tube rack, to safely store our experiment. One thing, looking back on that we should have done, is to make sure we had the same amount of liquid in each test tube. With different amounts of liquid all our tables will be off. We did not have a measuring cup at the time, so we estimated to the best of our abilities. In the second picture, I added the formula that we used to transfer the pH and the volume of the solution to the amount of hydroxide and hydrogen ions. In our tables I inputted all our results from the experiment and calculated the amount of hydroxide/ hydrogen ions (looking back on it I should have used a uniform method for the total number of drops added instead of having different ones for the acid and the base. I then transferred the data to some graphs which I plotted and included overhead. From my data I learned a lot about calculating the number of ions in a solution and using strict tables and graphs, and precise measurements to store our data.
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