Science Buddies: "Ask an Expert"

Hello. I'm just wondering if it is possible that pH of a solvent can change due to osmosis. I only need to back up my experiments with more research.

I've placed a slice of apple into each of the 9 cups of 3 different solutions, distilled water, water with baking soda, and water+vinegar. I had 3 different type of apples used: McIntosh, Granny Smith, and Golden Delicious. I had left the slices submerge in the solutions for 3 days.

I've noticed that the color of the litmus paper changed for the distilled water and shows that the pH level has fallen to around pH 5. However, for the basic solution (with baking soda) the pH level seems to have increased by 1. As for vinegar, it had stayed the same.

So I am confused at how my result turned out with an increase, a decrease, and one staying relatively the same. I suppose it does somewhat prove my hypothesis both correct and incorrect?

Can someone explain to me? How should I conclude my experiment?

Thank you.

Hi aimin_hi,

I'm not sure I understand your procedure exactly - did you leave the litmus paper in the solution over the three days? If so, that could be your problem since I wouldn't trust the litmus paper to read correctly over time. Is it possible for you to borrow a pH meter from your school or another lab nearby? That would allow you to make much more precise and frequent measurements.

Anyone else with more experience care to comment?

Oh, haha, nope. Sorry for not being so clear on my question.

I had tested the pH level of each cup once a day, using new litmus strips each time.

I'm just experimenting to demonstrate osmosis in the works through pH. Thus why I had placed a slice of apple into 3 different solutions.

It's a bit of a strange idea...

EDIT
Never mind! I was able to figure out why by myself. ^^ Thank you anyways!

I don't know if I should be writing my science fair question here, if it isn't am sorry and please tell me where.

I am in the ninth grade and I am doing a project on the antibiotic properties of two species of Echinecea , Pupurea and Angustifolia against bacterial culturs of E.coli.

could someone please help me with setting up my experiment?

I don't know where to get E.coli from and I don't know the kinds of materials I would need

I was also thinking about making an extract for both species, but I don't know how to do that

How do I find antibiotic properties zI know what in means but how do i record data
someone plese help me!
please!

Hi borborsmart508!

It's proper to open a new posting as a forum discussing your experiment. It would be useful to put a forward pointer on the old posting (this message) to the effect: "Please see my post, subject: ANTIBIOTIC PROPERTIES OF ECHINECEA, posted: Thu Sep 08, 2005 3:45 pm, in Life, Earth, and Social Sciences."

Giving such a pointer closes the original discussion neatly.

Note: anyone reading the post above would figure out what's going on. A seperate post from you would be better.