Can pH levels go beyond 14?

1 Answer
Aug 30, 2017

yes. example NaOH with molarity 10M/L [pH=15].

Explanation:

pH levels can surely go beyong 14 . if you check out some lower level books , you'll find 'pH range 0-14' but that doesn't make any sense.
pH varies from 0-14 at 25°C .
While reading one of the experiments in my bogus'lab manual ', i found pH of water at temperature more than 25°C to be less than 7 . But those books don't print why that's so.
The pH decreases on imcreasing temperature but yet steam isn't acidic . That leads to a practical conclusion that pH isn't static or say it doesn't has fixed range.

We know , pure water is neutral which means
pH = pOH.

therfore on adding both these we get the pH range .

Those rotten books print 'increase in H^(+) ions' as it's cause but don't really justify it .

Well, this was that pH range could contract and as per the question we gotta answer something different.

Now, pH could also be more than 7 (of pure water) but how?
That's the same answer as we have when we increase temperature .
with this i would conclude
pH is inversely proportional to delta temperature

Now , this was all like postulates without any justification .

Lets move to another question 'why does temperature have any effect on pH?'

The answer is related to concentration of H^(+) & OH^(-) ions [note H3O^(+) & H^(+) are one and the same things.

Throught several experiments it was found that the concemtration of Hydronium ions and hydroxide ions both is 10^(-7)M each . (conclusion water is neutral)

but as soon as we increase the temperature the rate of forward reaction increases or say the equilibrium shifts H2O breaks down into its respective conjucate base and acid [ions] thus there is an increase in concemtration of ions .
suppose the concentration increase from 10^(-7) to 10^(-5) .
this increase will be pf both cation amd anion thus solution stays neutral.

at 25°C
Kw =[H3O^(+)][OH^(-)]
Kw = 10^(-7) × 10^(-7) =
10^(-14)
Now if you want to find max pH its
-log (10^(-14))=14
but as in the example we took
the concentration to be 10^(-5) . so using the formula we get max pH as 10 . similarly we could also increase the ph range decreasing temperature.
Here's a link which includes some example and also explaination
https://chemistry.stackexchange.com/questions/6997/ph-range-outside-conventional-0-14
cheers!