Next, we were instructed to put in drops of Hydrochloric acid until the pH of our solution drops an entire whole number. It took our's a single drop to go down to a pH of 4.8. Then, we put 0.5 ml of the new solution into a test tube. We did the same process 2 more times. As you can see from the graph below, it took 5 more drops to get the liquid to a pH of 3.8 and 7 more drop after that for it to get to a pH of 2.8. In total, it took 13 drops to of Hydrochloric acid to get from a pH of 5.8 to a pH of 2.8.
The third and final part of the lab asked us to do what we did with acid, except now with a base. We got 100 ml of cabbage juice that measured at a pH of 5.8. Then we added 7 drops of Sodium hydroxide for it to get to a pH of 6.8 and 6 more drops after that for it to get to 7.8. Finally, as you can see from the graph below, we added 13 more drops for our solution to have a pH of 8.8. We added 26 drops of Sodium hydroxide in total.
As the picture below depicts, when the pH of the solution changed, so did the color of it. As we added more acid, the liquid became more of a red color, while as we added more base, the liquid became for of a blue/green color. If we ever wanted to know the pH of cabbage juice, we could use the photo below as an indicator to help us know that the pH is. The reason that we completed this lab was so that we could learn about how pH works and get more of a general feel for the affects of acids and bases so that when we go more in depth with pH it makes more sense. Now, next time we talk about pH, I will further understand the strength and efficiency that acids and bases have.
The first thing that really blew my mind about this lab was the sheer number of hydrogen ions and hydroxide ions that were in a few drops of liquid. When I realized that there were millions of ions packed into each drop, my jaw fell to the floor. As you can see in "Table 2: Acid" above, there were .0001 times 10 to the negative third power moles of hydrogen ions. That is a lot of molecules. Something else that was fascinating to me was the affect that so little acid had. Originally, we had 100 ml of cabbage juice. Each drop was about 0.5 ml. We only put one drop of acid, as the table shows, and it changed the solution by a whole pH. That is incredible. In conclusion, this lab greatly improved my knowledge of pH, and I am looking forward to more labs in the future.
