Preparation and standardization of 0.1 molar sodium hydroxide Solutions

 

Preparation and standardization of 0.1 molar sodium hydroxide Solutions

Preparation of 0.1 Molar Sodium hydroxide Solutions

¨  To prepare 0.1 Molar Sodium hydroxide solution take 4 gram of sodium hydroxide and dissolve in sufficient carbon-dioxide free water, and make final volume up to 1000ml with carbon-dioxide free water

¨  0.1M solution of NaOH

¨  Molecular weight of NaOH = 23+16+1= 40

¨  We need 4 gram of NaOH to make 1 liter solution of 0.1M concentration of NaOH

¨  Mass in gram= Molarity x molecular weight x required volume

                                                             1000

             Mass in gram = 0.1 x 40 x 1000     = 4 gram

                                                   1000

Standardization

¨  Crush slightly and then accurately weigh about 0.5gram (500mg) of Potassium biphthalate.

¨  Dried at 120◦C for 2 hours in an oven.

¨  Dissolve in 75ml carbon-dioxide free water.

¨  Add 2 drops of phenophthalein indicator.

¨  Titrate with 0.1 molar Sodium Hydroxide solution with constant stirring till a permanent

¨  Pink color is produced.

¨  Each ml of 0.1 molar sodium hydroxide solution is equal to 20.42 mg of Potassium biphthalate.

¨  Molarity

                              = weight of potassium biphthalate taken(mg)

                         molecular weight of potassium biphthalate x ml of 1 M NaOH used

¨  Molarity=

                         weight of potassium biphthalate taken(mg)

                                  204.22 x ml of 1 M HCl used

Note

¨  Standardization is only required when the solution is used for quantitative analysis.

¨  In case of qualitative analysis such as pH adjustment, dissolution medium or diluent there is no need of standardization.

 

 Presented by

Muhammad Atif

PhD Scholar Pharmaceutical Sciences 

Abdul Wali Khan University Mardan, Pakistan