Negative pH or a pH greater than 14

by Alan

For most solutions the pH value ranges from 0 to 14. However, in some rare cases you may see a pH value out of the normal range.

Extremely acidic or extremely basic substances may have pH less than 0 or greater than 14.

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Nov 16, 2012
ph -ve how?
by: ash

a ph value of -1 implies that {H+} CONCENTRATION in the solution is greater than 1M. so a ph value can be negative.

Jan 07, 2012
Regarding pH value
by: Md. Shahid

Why pH range is 0-14?

Dec 18, 2010
About negative pH
by: Dr CPR Nair

Theoretically, a solution can have a negative pH without disobeying the law of ionic product of water(Kw=10E-14). Very concentrated acid solutions with H+ ion concentrations greater than 1 mole/L can show negative pH. e.g. if the H+ ion concentration is 10 molar it is only required that the OH- concentration be 10E-15mole/L to make up a Kw of 10E-14.

In fact, OH- ion concentration can go down to at least one ion per litre( 1/6.23*10E23 mole) making a theoretical pOH of the order of ~ 24!( since pOH is ~ 24, pH can be hypothetically -10!). It is true that log scale considers activity rather than bsolute concentrations, but it is difficult to comprehend the scale of pH from 0 to 14.

How can one state that the activity of 10 molar HCl solution is 1 or near to 1, the scale of pH from 0-14 is bizarre.

May 17, 2010
pH range
by: Dan

How far from 0 or 14 can you go?

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