IIT JEE , AIEEE Forum - Chemistry , Physical Chemistry

voldemort00

in case of acid buffer, there is a weak acid and salt of its conjugate base(strong base)

since the acid is weak and and base is strong than should'nt acidic buffer has ph>7

rahul_12345

Okay, now consider an example

Take acetic acid and the salt of it's conjugate base sodium acetate

The acid dissociation constant for acetic acid-sodium acetate is given by the equation:

$\mathrm{K_a = \frac{[H^+][CH_3COO^-]}{[CH_3COOH]}}$

Since this equilibrium only involves a weak acid and base, it can be assumed that ionization of the acetic acid and hydrolysis of the acetate ions are negligible. In a buffer consisting of equal amounts of acetic acid and sodium acetate, the equilibrium equation simplifies to

K a = [H +]

,

and the PH of the buffer as is equal to the pK_a.

So the PH of the buffer purely depends upon the concentration of the acid and the salt of it's conjugate base

arun-rashi

buffer solution atre solution with reserve Ph on adding small amount of acid,base or water.these are of three types acidic buffer by weak acid and salt of this strong base Ph calculeted by henderson formula Ph =Pka +log [salt/acid] ph control by H+ion so always less then 7,for basic more then 7 formed by weak base and salt of this with strong acid while neutral buffer CH3COONH4 ph is almost 7.

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