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Home » Class 11 » Chemistry » Ionic Equilibrium » pH

pH

Last Updated on February 16, 2023 By Mrs Shilpi Nagpal

A solution may be neutral, acidic or alkaline.

ionic products

Kw = 1 × 10-14 at 298 K

To express the acidity or alkalinity of a solution, it is sufficient to express only the H3O+ ion concentration.

Sorensen , in 1909 , suggested a convenient method of expressing the H3O+ ion concentration in terms of pH.

The symbol has been taken from the Danish word potenz de hydrogen ion which mean power of hydrogen ion.

pH of a solution is defined as negative logarithm of hydrogen ion concentration.

pH

pH scale

The pH scale range is taken as 0 to 14 for practical purpose.

pH scale

Relationship between pH and pOH

relationship between pH and pOH

Relationship between Ka and Kb or pKa and pKb

kw

log kw = log ka + log kb

– log kw = –log ka – log kb

–log ka – log kb  = – log 10-14

pKa + pKb = pKw = 14

Limitation of pH scale

The pH value of the solutions do not give the exact idea of their relative strength

Measurement of pH

Accurate measurement of pH of a solution is done with the help of an instrument , called pH- meter.

Approximate pH can be determined with the help of pH papers which show different colours when dipped in solution of different pH.

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Filed Under: Chemistry, Class 11, Ionic Equilibrium Tagged With: Limitation of pH scale, Measurement of pH, pH, pH scale, Relationship between Ka and Kb or pKa and pKb, Relationship between pH and pOH, Sorensen

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Comments

  1. Rajesh says

    April 23, 2019 at 1:59 pm

    Thank you very much for this post (ph class 11), thanks a lot

  2. Aryan sudipta halder says

    November 3, 2020 at 11:54 pm

    Really proved to be very useful..

  3. Khadija says

    April 7, 2021 at 11:06 pm

    To be honest best answer

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