Question
A certain buffer is made by mixing sodium formate and formic acid in water. With the help of equations explain how this buffer neutralizes addition of a small amount of an acid or a base?
✓
Answer
$\text{HCOONa}\xrightarrow{\ \ \ \ \ \ \ \ \ \ }\text{HCOO}^-+\text{Na}^+$
$\text{HCOOH}\rightleftharpoons\text{HCOO}^-+\text{H}^+$
HCOO- is common ion in the above acidic buffer. When small amount of H+ ions is added, these H+ ions combine with HCOO- which are in excess to form HCOOH back and [H+]remains practically same, so pH remains constant. When small amount of OH- ions are added, OH- ions will take up H+ and association of HCOOH will increase so as to maintain concentration of H+ ions. So, pH is not affected.
$\text{HCOOH}\rightleftharpoons\text{HCOO}^-+\text{H}^+$
HCOO- is common ion in the above acidic buffer. When small amount of H+ ions is added, these H+ ions combine with HCOO- which are in excess to form HCOOH back and [H+]remains practically same, so pH remains constant. When small amount of OH- ions are added, OH- ions will take up H+ and association of HCOOH will increase so as to maintain concentration of H+ ions. So, pH is not affected.
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