Question

Any buffer can be used as a buffer up to:

• A. $10pH$ unts
• B. $5pH$ units
• C. $2pH$ units
• D. $1pH$ units

Answer 1

Answer: (C)

$2pH$ units

Buffer capacity of the solution is maximum under the following condition :

[Salt] $=$ [Acid] (in acid buffer)

[Salt] $=$ [Base] (in base buffer)

If, $pH={pK}_a$ or $pOH={pK}_b$ then buffer will be efficient.

So buffer can be used in the range between $pH-1$ to $pH+1$ of its original $pH$. Any buffer can be used as a buffer up to $2pH$ units.