pH pOH and Ionization of Water

Ionization of Water

Water ionize as given below;

H2O(l) ↔ H+(aq) + OH-(aq)

In pure water concentrations of H+ and OH- ions are equal to each other and at 25 0C, they have concentration 1x10-7 M. Since concentration of ion in pure water is too  low, it is a bad electric conductor.

As in the case of pure water mediums having [H+]=[OH-] concentration are called neutral mediums. In water solutions multiplication of [H+] and [OH-] is constant and at 25 0C it is 1x10-14. This number is also called ionization constant of pure water.

If acid is added to pure water;

[H+]>1x10-7 M and [OH-]<1x10-7

If base is added to pure water;

[OH-]>1x10-7 M and [H+]<1x10-7

To sum up we can say that;

  • If concentration of  [H+] = [OH-]=10-7M, then solution is neutral.
  • If concentration of  [H+] > [OH-] or [H+]>10-7M and [OH-]<10-7 M, then solution is acidic.
  • If concentration of  [OH-]>[H+] or [H+]<10-7M and [OH-]>10-7 M, then solution is basic.

Example: HCl having volume 224 cm3 under standard conditions mixed with pure water and form 1 L solution. Which ones of the following statements are true for this solution?

I. Concentration of solution is 10-2 molar.

II. Concentration of H+ ion is 10-2 molar.

III. Concentration of OH- ion is 10-12 molar.


We find mole of HCl  gas under standard conditions.

1 mole gas has volume 22,4 L and 1 L= 1000 cm3

nHCl=224/22400=0,01 mol

Molarity of HC solution is;

[HCl]=0,01/1=0,01 M or [HCl]=10-2 M I is true

Since HCl is strong acid, it is completely ionize in solution. Thus, concentration of H+ ion is equal to concentration of HCl. II is true.



[OH-]=10-12 molar III is true.


pH and pOH

In liquid solutions, to state concentrations of H+ and OH- ions pH and pOH concepts are used. We can show pH and pOH in terms of concentration as;




Solution having molar concentration of H+=10-2 M has pH=2 and solution having molar concentration of OH-=10-5 has pOH=5. To remember logarithmic calculations;

[H+].[OH-]=10-14 log of this equation;

log[H+] + log[OH-]=-14

-log[H+] - log[OH-]=14

pH + pOH = 14

In acid solutions, [H+]>10-7 or pH<7

In base solutions [H+]<10-7 or pH>7

  • If 7>pH>0 acidic solution
  • If 14>pH>7 basic solution
  • If pH=7 neutral solution

Picture given below summarizes what we try to explain above;















Example: Which ones of thee following statements are true for water solutions?

I. If pH=pOH=7 , then solution is neutral

II. If [H+]>10-7 then pH<7

III. If [OH-]>[H+] then pH<7


I is true is pH=pOH=7

If [H+]>10-7 M then pH<7  II is true

If [OH-]>[H+] then pH>7 III is false.


Acids and Bases Exams and  Problem Solutions


ph and poh concepts
pH and poH ionization of water
pH,pOH ionization of water
poh of pure water
what is 7 of water ph or poh
ph and poh of pure water
pOH 7; solution is
ionization of water pH and pOH
solution with a ph equal to 2 has a poh equal to
images of acid solutions]
how to solve Hcl ionizes completely in water what is the H ion of a 01m solution
ionization of water in chemistry
ph and ionization
poh concepts
ionization of water ph poh
[h]+ *[oh]- =10-14
ionization chemistry tutorial ph
pH ionization of water
what is ionization of water chemistry
ionisation of water in chemistry 12th
online water chemistry
ionization of water example
ph ionization
ionization of water
poH in terms of oh- conc
pH of HCL with concentration of 1x10^2-
water ionization in chemistry
Explain PH and Ionisation
pOH equal zero
is ph equal to poh
mole concept ionization
can pOH ever be equal to 0
ionization of solutions chemistry
ionisation and ph
PH of 10 -8 molar solution in water
Ionisation of water and pH
Ionization and pH example
why would we say that a solution with a H+ concentration of 1x10^-7 M is said to be neutral
chemistry 12 ionization of water
ionization of water includes ph
ph poh pure water
Acids And Bases Ph Scale
Ionisation of water
ph and ionisation
examples of ionization of water
pOH is equal to what in Chemistry]
which of the follwoing is true about a basic solution[OH-] 10-7 and pOH 7
if poh of a water solution is 120 what is the ph