SATHEE: Equilibrium - Result Question 78

Equilibrium - Result Question 78

####82. Buffer solutions have constant acidity and alkalinity because

[2012]

(a) these give unionised acid or base on reaction with added acid or alkali.

(b) acids and alkalies in these solutions are shielded from attack by other ions.

(d) they have fixed value of $p H$

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Solution:

(a) Constant acidity and alkalinity of buffer solution is due to the unionised acid or base.

Lets take an example of an acidic buffer $C H_{3} C O O H$ and $C H_{3} C O O N a$ .

$C H_{3} C O O H \to C H_{3} C O O^{-} + H^{+}$ ;

$C H_{3} C O O N a \to C H_{3} C O O^{-} + N a^{+}$

when few drops of $H C l$ are added to this buffer, the $H^{+}$ of $H C l$ immediatly combine with $C H_{3} C O O^{-}$ ions to form undissociated acetic acid molecules. Thus there will be no $H^{+}$ ions to combine with $C H_{3} C O O^{-}$ ions to form undissociated acetic acid molecules. Thus there will be no appreciable change in its $p H$ value. Likewise if few drops of $N a O H$ are added, the $O H^{-}$ ions will combine with $H^{+}$ ions to form unionised water molecule. Thus $p H$ of solution will remain constant.

Equilibrium - Result Question 78

Solution:

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Equilibrium - Result Question 78

Solution:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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