Aim: How to convert between pH and concentrations.
Activity: Draw the pH scale.
Notes: Sörenson defined pH as the negative logarithm of the hydrogen ion concentration.
pH = – log [H+]
Remember that sometimes H3O+ is written, so
pH = – log [H3O+]
means the same thing.
So let’s try a simple problem: The [H+] in a solution is measured to be 0.010 M. What is the pH?
The solution is pretty straightforward. Plug the [H+] into the pH definition:
pH = – log 0.010
An alternate way to write this is:
pH = – log 10¯2
Since the log of 10¯2 is -2, we have:
pH = – (- 2)
Which, of course, is 2.