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RE: Acid-Base Balance in the Human Body: Mechanisms of Regulation
Really appreciated @urost!
I actually skipped a bit of the explanation of pH so it is not too complicated. For example, when measuring pH for buffers like carbonic and phosphate, we actually do the calculation in the following way (as they are weak acids):
pH = pKa - log ([Acid]/[Base])
pKa = logarithm of the acid constant
[acid] = concentration of acid
[base] = concentration of base
And thanks for your notes, I almost forgot pH can also have higher or lower values (like negative in concentrated HCl). Otherwise, I understood that it was defined as the negative logarithm of the concentration, but I need to check that one out.
Thank you a lot!
No problem! The thing you wrote is actually called Henderson-Hasselbalch equation. It fails in multiple cases (as you have to make a few assumptions during derivation), such as when the ratio of acid and base is drastically skewed, or the solution is either too concentrated or diluted. The H-H equation is still very useful for approximating the pH of some systems. Also, pH is dependent on temperature (think thermodynamics!), for example pH of water at 0 degrees C is something around 7.5 (please check the actual value, this is from my memory), but this doesn't mean that water gets alkaline when you lower the temperature. The story of pH and measuring it is much more complicated, and maybe it deserves a post on its own!
You should write this post