Science project question?

Question

So I would like to pursue this Science Fair project, but I have a few questions on terminology. If you could explain it as simply as possible that would be great. I am wondering what a buffer capacity/buffer solution is? It look as if it had a lot to do with math. Also, I would like to know what this HC1 solution is.

Here's the project: http://scssi.scetv.org/mims/schools/blhs/science/y98/joshm3.htm

Thank you.

Answer 1

First of all: it's a HCl solution, which is an acid called Hydrochloric acid.

When you add acids to a solution the pH value of that solution will drop. However some solutions can cope with a small amount of acid without a drop in its pH value. This tolerance for acids is the buffer capacity of the solution.

Distilled water is pH neutral, meaning it has a pH of 7. In your experiment you will have 4 types of 'solutions': distilled water, plus samples from 3 different sources.

First you start adding HCl to distilled water until the pH value equals 4. Now you know how much acid you need to get to this pH.

When you repeat this for the other samples it might be possible that you need to add more acid to reach a pH of 4. This difference in the amount of acid is the buffer capacity of the sample compared to distilled water.