Wednesday, November 17, 2010

How can I slightly change the pH of water?

Hi.

For Biology, I have to compare how much carbon dioxide is produced through cellular respiration for a plant and animal. We have an Elodea (aquatic plant) and an aquatic snail. I want to change the pH of the water to see how it affects their respiration rates. And we have to be ethical with the plant and snail.



So how can I slightly increase and slightly decrease the pH of the water but keep it safe so that it doesn't kill the plant or snail. Thanks :DHow can I slightly change the pH of water?
I don't know how you can tell for sure how much pH change will hurt that plant or that snail unless you can find published information.



However, you can easily reduce the pH by adding a little weak acid, such as vinegar. If you only add a little you will only get a tiny change.



You can raise the pH by adding a weak base, perhaps a little baking soda dissolved in warm water.



How much you should add depends on what change you are going for. It is difficult to calculate this accurately because of impurities in most water and variation in acid/base strengths.



You could start with two containers with the same amount of water that you have with the wildlife. You could measure the pH and then start adding (maybe one ml at a time) your weak acid, and after each addition (stir first) see if you can measure a pH change. When you get the pH change you want, then you know how much to add. Do the same with a new container of water and the base.



good luckHow can I slightly change the pH of water?
Add highly concentrated nitric acid. HNO3 doesn't dissociate, so even if you add a lot, it shouldn't change the pH that much.

No comments:

Post a Comment