So getting back to pH. If you have pure water, of any given sample, that sample will have a pH of 7. Now this magical number is right in the middle of the pH scale, therefore we can say that the pH of the sample of water we are working with is neutral. The water is neither acidic nor base.
So taking what we know about the pH scale we know that the mathematical formula is written as such 1.0 x 10-7 for a sample of water with a neutral pH. Okay that is nice and everything but what does it mean? It means this. In Pure water a small percentage of the molecules are dissociated into H+ and OH- ions, and because the concentrations of these two elements are equal, this pH is said to be neutral.
In our other sample of water with a pH reading of 4, that sample contains more H+ than OH- ions. By the way I forgot to mention what that OH- ion is, it has a name, its a Hydroxyl Ion, all it really is, is a H2O molecule that lost a molecule of hydrogen. You have heard the term free radical; well this is an example of one!
So now you know what pH is, and how it is measured, and why it can be changed. Oh wait, take a step back, we didnt discuss this yet did we. Well we will, but for now we are going to let this be a shorter chapter. So go back, and review if you need to the concepts discussed here in the third chapter.
Previoua Page > Basic Chemistry - Page 1