Home » Ask & Discuss » Chemistry. » Physical Chemistry « Back to Discussion

Physical Chemistry

Cool goIITian

Joined:	22 Nov 2006
Post:	37

29 Apr 2008 16:00:48 IST

0 People liked this

516

1. Why is the pH reading scale only from 0 to 14?Why not 15, 16...???

None

1. Why is the pH reading scale only from 0 to 14?Why not 15, 16...???

Share this article on:

Comments (7)

harsh _27

Blazing goIITian

Joined: 21 Apr 2007

Posts: 897

29 Apr 2008 16:18:38 IST

Like 0 people liked this

It can be 15,16,.... and also negative.

It all depends on the solvent we are using and the temperature.

anushree

Cool goIITian

Joined: 3 Apr 2008

Posts: 40

29 Apr 2008 16:51:16 IST

Like 0 people liked this

hey there.....see basically ph is -ve log of hydrogen ion concentration so it means when the ph of a sol. is say 4 actually the hydrogen ion concentration is ${10}^{-4}$ M .so according to the various experiments conducted it is generally seen that the hydrogen ion conc. varies from ${10}^{-1} to {10}^{-14}$ ..........therefore only 1 to 14 numbers are required to determine a ph scale

hope u got it cheers!!!! rate this answer if helpfull.........

Sagar Vaze

Blazing goIITian

Joined: 11 Apr 2008

Posts: 315

29 Apr 2008 18:54:38 IST

Like 0 people liked this

pH can be anything if you have concentration of strong acid greater than 1 molar then pH becomes negative. similarly for concetrated base pH > 14

chemicaltester

Scorching goIITian

Joined: 12 Mar 2008

Posts: 233

29 Apr 2008 20:29:39 IST

Like 0 people liked this

now seee
ph is nothing but negative of log of h + ions
the minum ph can be 14 if h+ ions is 10^-14
if the temprature is increased this product increses
but if we decrease tbe temp the ionic product decreses
so , the ph can be 15 .16 at certain lower temprature than 298k
so if we decreses temp like till 30k or something like that
we can do it
but the ph can never be less than zero

Chirag Sangani

Forum Expert

Joined: 12 Dec 2007

Posts: 611

30 Apr 2008 18:48:15 IST

Like 0 people liked this

for dilute solutions pH is approximately -log [H+], however, as the solution becomes concentrated, the formula changes. formally, pH is the measure of the activity of the hydrogen ions. for dilute solutions, activity equals molar concentration, but they are different for concentrated solutions. Read wikipedia for more info: http://en.wikipedia.org/wiki/PH

Krishna Gopal Singh

Forum Expert

Joined: 29 Dec 2006

Posts: 5153

30 Apr 2008 19:15:08 IST

Like 0 people liked this

Yes it can be 15 (I am doubtfull about 16 though). Dissolve 400g NaOH in water to make 1 litre solution and its pH will be 15

djdylan2000. bits goa eee

Blazing goIITian

Joined: 7 Feb 2007

Posts: 1608

2 May 2008 12:48:08 IST

Like 0 people liked this

You can make it >14, but you'll have to use a solvent other than water. The reason is that water splits up to H+ and OH- with a Kw value of 14. So there are 10^-14 moles of H+ion concentration in the most basic solution of water.

Quick Reply

Reply

	Some HTML allowed.
	Keep your comments above the belt or risk having them deleted.
	Signup for a avatar to have your pictures show up by your comment
	If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team