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Home » Class 11 » Chemistry » Ionic Equilibrium » pH

pH

Last Updated on July 3, 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.

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

About Mrs Shilpi Nagpal

Author of this website, Mrs. Shilpi Nagpal is MSc (Hons, Chemistry) and BSc (Hons, Chemistry) from Delhi University, B.Ed. (I. P. University) and has many years of experience in teaching. She has started this educational website with the mindset of spreading free education to everyone.

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  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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