Wednesday, July 15, 2009

The Polar Bears Are Decieving

Today, we worked on our final project in the lab all day. My feet hurt from standing for awhile and I have a mark on my cheeks from the goggles, but we don't have to go into the lab tomorrow to finish up.

My group, which contains four others, has to find the concentration of phosphoric acid in Coca-Cola. Coke is something I drink at least once a week, and I had no idea that is was so acidic. Its pH is around 2.6, and after reading the ingredients label, I found out it was actually listed as an ingredient.

First, we had to flatten out the Cola, so I purchased a bottle and left it open overnight in my room. I brought it to the lab the next morning, and it was pretty flat. Then, we prepared three samples of KHP between .2 and .25 grams to put into distilled water. We added three drops of phenolphthalein to each sample. Then, we prepared a solution of NaOH and distilled water and we titrated the KHP mixture to find out the concentration of the NaOH solution.

The first time we did, two out of three of our samples were over-titrated, and the mixture turned purple instead of a pale, clear pink. We restarted the process again, and our three samples turned out great. We found the concentration of our NaOH and then we calibrated the pH meter of the MicroLab program.

Next, we measured out one hundred milliliters of Coca-Cola, both fizzy and flat, and added the NaOH using a burette and a drop counter, which told us the volume of the NaOH solution used. The fizzy Coca-Cola's titration curve looked a bit off, so from then on we just stuck to flat Coca-Cola because the titration curve looked almost the same as one from a previous experiment. We did the flat Coca-Cola test twice.

Then, our mentor, Mike, decided to give us phosphoric acid so we could compare it to the Coca-Cola results. We didn't have enough NaOH solution, so we had to prepare the three samples of KHP and phenolphthalein with distilled water mixture and titrate it three times. We were much quicker this time, and we did find out that there was a small difference between the concentration of the previous NaOH solution. At first, we diluted .01 molar phosphoric acid, but that took too long, and we were running out of NaOH solution, so we switched to .04 molar phosphoric acid and that worked faster. The titration curve looked great.

We cleaned up for the day, and tomorrow we'll be working on our poster. Our previous day's research told us that phosphoric acid is linked to cancer in rats, erosion of teeth, bone loss, and had an effect on the oral mucosa of rats. Those Coca-Cola polar bears probably don't know the effect of phosphoric acid on them. Smelling that cola the whole day did make me want to drink some at lunch, though.

After class, we had our daily meeting with Mrs. Lilhanand. She just visited Swarthmore, and she said it had really beautiful scenery. From one of the brochures, it says that 88% of all applicants get admitted into medical school. I was excited, and I will see if Swarthmore is going to be at the college fair tomorrow at lunch.

In other news, my time management is pretty horrible. I find myself taking naps, and telling myself to wake up after two hours to get my work done, but I just ignore my alarm, continue to sleep, and rush it in the morning. I've got two more days of classes, so I better get rid of this habit fast, especially since our project is due on Friday morning and we have to present to the chemistry department and graduate students.


Madeline Kronenberg said...


Thanks for the comprehensive post -- I feel sorry for those Polar Bears myself. Sounds like your project is very comprehensive -- I'd love to see a picture of your poster when it is done.

Swarthmore does sound like a wonderful school and I hope you do get to meet with them today at the college fair.

The first step in managing time is realizing that you are "horrible" at it. So, now that you know that you simply "take charge" and don't let yourself ignore the alarm clock. I'm confident you'll handle this. Enjoy the fair and good luck with your presentation.

Clearly you

Don Gosney said...


Those of us who have been around know all too well of the acidic nature of Coca Cola. We use it to remove rust, we pour it down our sinks to unclog drains (it even eats the hair in the sink trap) and we’ve used it in toilets to unstain the porcelain. Now, just imagine what it does to your stomach. It doesn’t make your teeth look all that good, either.

As for the time management problem, I’m betting that’s a lost cause while you’re there. With only two days left it’s not very likely that you’ll be able to rehabilitate yourself and make it count.

Once you return home, however, that might be a project to help finish out the summer. You’re at a point in your life now, Cristina, where this is going to be a critical issue for you and once you’ve mastered time management, your senior year will be much easier for you and a lot of people should notice the difference.

Post a Comment