What are some common mistakes students make with pH?
There are 2 commom mistakes that students make:
One, not remembering what end of the pH scale is acidic and which is basic. I tell my students that it is like counting and saying the alphabet. When you do so, you count 0-14 and you say the alphabet, A,B... So, the 0 end corresponds to the A or acid and the 14 end corresponds to B or base.
The second mistake is in thinking that pH is the same as concentration. pH measures the ability of an acid to give up hydrogen ions (H+1) and a base to give up hydroxide ions (OH-1). You can find the pH by using hydrion paper or by using the formula:
(pH = - log of the hydrogen ion concentration).
Concentration is the measure of how much acid or base is dissolved in water. You can find concentration by titration and use the formula:
(Molarity of the acid x ml of acid = Molarity of the base x ml of base). Or, you may be able to use this formula with bases since they are sold as solids: (Molarity = grams of base used / liters of water x formula mass of the base).