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| The pH Scale |
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| The strength of acids and bases can be expressed in terms of the concentration of the hydronium ions or hydroxyl ions in a solution. The concentration of hydronium ions in a solution can be expressed as moles of hydronium ions per litre of solution. This is expressed by a term called 'pH' which represents the 'power of hydrogen ion concentration' in solution. |
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| The pH is defined as: 'the negative logarithm (to the base 10) of the hydrogen ion concentration, expressed in moles per litre'; i.e., |
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| pH = - log10 [H+] |
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| where [H+] is the hydrogen ion concentration in molecule/Litre. |
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| The strength of various acids and bases is expressed on the pH scale. The pH scale is a 14 point scale, which expresses the strength of an acid or a base in terms of the hydronium ion concentration. The range from 0 to 14 gives a measurement of comparative strength of acid and base solutions (Fig. 8.4). |
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| Pure water and other neutral solutions have a pH value of 7. A pH value less than 7 indicates that the solution is acidic, and a pH value greater than 7 indicates that the solution is basic. |
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Study of Acids Bases and Salts
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