 ## Buffer Solutions

pKa value of a weak acid with known dissociation constant
pH value of a salt/acid buffer system
pH value of a base/salt buffer system
Molar ratio of salt/acid required to prepare desired pH
Components of a buffer solution to yield a specific volume
Change in pH with addition of an acid or base

### pKa value of a weak acid with known dissociation constant

 Dissociation constant of weak acid : X 10 pKa = Top

### pH value of a salt/acid buffer system (Buffer equation for weak acids)

 Molar concentration of salt: M Molar concentration of acid: M pKa value of acid: pH = Top

### pH value of a base/salt buffer system (Buffer equation for weak bases)

 Molar concentration of base: M Molar concentration of salt: M Kb value of base: X 10 (or) pKb value of base: pH = Top

### Molar ratio of salt/acid required to prepare a buffer of desired pH

 Desired pH: pKa value of acid: Molar ratio of salt/acid = Top

### To calculate the amount of components of a buffer solution to yield a specific volume

 Molar ratio of salt to acid: : Total buffer concentration (mol/L): X 10 Gram molecular weight of salt: Gram molecular weight of acid: Volume of buffer solution to be prepared: ml Quantity of salt required (g/L)= Quantity of acid required (g/L)= Top

### To calculate change in pH with addition of acid or base

Molar concentration of salt in one litre of the buffer solution (M):
Molar concentration of acid in one litre of the buffer solution (M):
Molar Concentration of
 base acid
to be added (M)
pKa value of acid in the buffer:
Initial pH =
Altered pH =
Top