Sciencemadness Discussion Board

pH and alkalinity

prole - 25-12-2007 at 08:12

I'm studying for a test, which covers, in part, soil chemistry. In reviewing the pH info., I find that there is no direct relationship between a basic pH and alkalinity. I have always equated a basic pH to alkalinity, have used them interchangeably, and am surprised and confused to find this is not so.
I understood pH to be the concentration of H+ or OH- in aqueous solution for acidity and alkalinity, respectively. Now I see that the concentration of OH- does not refer to alkalinity at all. My text says alkalinity refers to the conc. of (bi)carbonates only. Thus, a high pH may be basic, but not alkaline if no carbonates are present, and a high pH is basic and alkaline if carbonates are indeed present. Do I now have a deeper understanding of pH and alkalinity, or is my text misinforming me?
I've taken various chem courses in my life, but I don't recall learning the distinction between pH and alkalinity, rather, being taught that basic pH=sweet=alkaline. Can/will anyone confirm this?

[Edited on 12/25/2007 by prole]

solo - 25-12-2007 at 08:53

Read.....solo

http://en.wikipedia.org/wiki/Alkaline
http://en.wikipedia.org/wiki/PH