Calculate the volume of 0.500 M HCOOH and 0.500 M HCOONa required to prepare 0.100 L of pH = 4.25 buffer with a buffer
strength of 0.100 M. The pk, of HCOOH is 3.75.
нсоон:
HCOONa:

The volume of HCOOH is 0.003 Lt and the volume of HCOONa is 0.017 LT.

Explanation:

For acidic buffer

PH = Pka + log

4.25 = 3.75 + log

log = 0.75

log = 5.62 is considered as equation 1.

Let V₁ ml of HCOOH and V₂ml of HCOONA was mixed and the final volume is 100 ml .

V₁ *0.5 + V₂ *0.5 =0.1 * 100

V₁+V₂ = = 20 is the second equation.

Now concentration of salt and acid are

V₂ [salt] = 0.5/100  and v₁ [acid] = 0.5/100

by substituting these in equation 1 we get,

= 5.62

V₂ = V₁ * 5.62 is the 3 rd equation

by solving 2 and 3 we get,

5.62 V₁ + V₁ = 20

= 6.62 V₁ = 20

V₁ = 3.02 ml

V₁ = 0.003 LT

V₂ = V₁ * 5.62

V₂ = 0.017 LT

Hence the volume of  HCOOH is 0.003 Lt and the volume of HCOONa is 0.017 LT.

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.