View Full Version : How do I calculate correct concentrations for pH?


synthesizer-patel
11-13-08, 11:29 AM
I need to get a sample of seawater to a particular pH level by adding H2CO3 - presumably if I know the pH / molarity of the acid and the pH and volume of the seawater, it should be easy to calculate the volume of acid I need without messing around with trial and error - I'm sure I've done this before but I'm buggered if I can remember how its done - can anyone refresh my memory please?

Trippy
11-13-08, 11:32 AM
[H] =10^-pH

synthesizer-patel
11-14-08, 02:37 PM
[H] =10^-pH

when they discover mathematical dyslexia it'll be named after me
so once again in english for the hard of thinking please :)

Trippy
11-14-08, 02:44 PM
when they discover mathematical dyslexia it'll be named after me
so once again in english for the hard of thinking please :)

The concentration of Hydrogen Ions in a solution is equal to ten to the power of the negative pH number.

In other words - for a solution with pH = 7, the concentration of Hydrogen Ions in that solution 1x10^-7 mol/l

For a solution with pH = 1 the concentration of Hydrogen Ions is 0.1 mol/l.

Another way of thinking about it is that pH = -log([H]) if that helps?

synthesizer-patel
11-14-08, 03:19 PM
The concentration of Hydrogen Ions in a solution is equal to ten to the power of the negative pH number.

In other words - for a solution with pH = 7, the concentration of Hydrogen Ions in that solution 1x10^-7 mol/l

For a solution with pH = 1 the concentration of Hydrogen Ions is 0.1 mol/l.

Another way of thinking about it is that pH = -log([H]) if that helps?

Ah! - you're using the ^ symbol as the "to the power of" symbol I was looking at it as the mathematical function "and" - makes sense now - cheers dude