Preparation of Normal Solutions

Preparation of Normal Solutions


Preparation of Normal Solution 

Preparation of 0.05N KOH Methanolic: 
Preparation of normal solutions

Take Potassium Hydroxide A.R grade. Weigh about 3.5 gm of potassium hydroxide in beaker and add 5 ml of water and dissolve it by stirring than add pure methanol to produce 1000 ml and mix well. Allow the solution to stand in tightly stopper bottle for 24 hours. After 24 hours, filter and standardize the solution then use for analysis.
NOTE: Store in a tightly stopper bottle and protect from light.

Standardization of 0.05 N KOH:

Take about 5 gm of potassium hydrogen phthalate in a Petri dish and dried at 1050C for two hours. Weight about 0.35 gm substance and dissolve in 50 ml of distilled water and add five drops of phenolphthalein indicator. Titrate it against the potassium hydroxide solution until a permanent pink colour and note the burette reading.
Repeat the above process in triplet set.

                               Wt of Substance x 1000 
CALCULATION =------------------------------
                                      204.22 x B.R

Preparation of 0.5 N NaOH:

Take Sodium Hydroxide A.R grade. Weigh about  20 gm of  sodium hydroxide in beaker and add 150 ml of carbon dioxide free water. Dissolve it by stirring and cool to room temperature than add sufficient carbon dioxide free water to produce 1000 ml and mix well and filter the sodium hydroxide solution and allow the solution to stand in tightly stopper bottle for 24 hours. After 24 hours standardize the solution then use for analysis.
NOTE: Store in a tightly stopper bottle and protect from light. 

Standardization of 0.5 N Sodium Hydroxide Solutions:

Weigh accurately about 2.0 gm of potassium hydrogen phthalate in a 250 ml conical flask previously dried at 1050C for two hours than add 50 ml distilled water and dissolve it. Add 5 drops of phenolphthalein solution. Titrate it against the sodium hydroxide solution until a permanent pink colour is produced then note the burette reading.
Repeat the above process in triplet set.

                                 Wt of Substance x 1000 
CALCULATION =------------------------------
                                      204.22 x B.R

Question: Why sodium hydroxide solution filtered before standardization.?
Answer: Sodium hydroxide solution react with CO2 which is present in water or atmosphere and make a sodium carbonate precipitate.
                                   2NaOH + CO2  --------------->  Na2CO3 +  H2

Preparation of 0.1 N AgNO3:   

Take Silver nitrate A.R grade.Take about 17 gm of Silver Nitrate in beaker by weight than add 150 ml of carbon dioxide free water. Dissolve it by stirring than add sufficient Carbon dioxide free water to produce 1000 ml and mix well. Transfer the solution in amber colour bottle and allow the solution to stand in tightly stopper bottle for 24 hours. After 24 hours standardize the solution then use for analysis.
NOTE: Store in a tightly stopper bottle and protect from light.
Question: Why amber colour bottle used storage for Silver Nitrate Solution.?
Answer: Silver Nitrate is highly light sensitive so it`s storage in amber colour bottle from protection of light..

Standardization of 0.1 N Silver Nitrate Solution:

Weigh accurately about 0.1 gm of Sodium chloride previously dried at 1100C for two hours and add three drops of Eosin solution than add 5 ml of water and 5 ml of acetic acid dissolve it than add 50 ml of alcohol.Stir with magnetic stirrer for homogeneous mixture. Titrate with the silver nitrate solution until a reddish brown colour is produced and note the burette reading.
Repeat the above process in triplet set.

                                 Wt of Substance x 1000 
CALCULATION =------------------------------
                                      58.44 x B.R

Preparation of 0.5 N HCL:

Take Hydrochloric Acid A.R grade.Take about 45 ml of Hydrochloric Acid in beaker and add 150 ml of carbon dioxide free water. Dissolve it by stirring and add sufficient carbon dioxide free water to produce 1000 ml and mix well. Transfer the solution in reagent bottle. Allow the solution to stand in tightly stopper bottle for 24 hours. After 24 hours standardizes the solution than use for analysis.
NOTE: Store in a tightly stopper bottle and protect from light.

Standardization of 0.5 N HCl:

Weigh accurately about 0.75 gm of anhydrous sodium carbonate previously dried at 1050C for two hours.Dissolve in 50 ml distilled water than add 0.5 ml of methyl red solution.Add the acid slowly from a burette with constant stirring until the solution becomes faintly pink.Heat the solution to boil and cool than Titrate again.Repeat the above process in triplet set and note the reading.
                                                                                                                                                                   
                                 Wt of Substance x 1000 
CALCULATION =------------------------------
                                        52.99 x B.R

Preparation of 0.1 N Ferrous ammonium sulphate: 

Take Ferrous ammonium sulphate A.R grade. Take about 40 gm of ferrous ammonium sulphate in beaker and add 200 ml previously cooled water and 40 ml of H2SODissolve it by stirring than add sufficient carbon dioxide free water to produce 1000 ml and mix well.Transfer the solution in reagent bottle and allow the solution to stand in tightly stopper bottle for 24 hours. After 24 hours standardize the solution then use for analysis.

NOTE: Store in a tightly stopper bottle and protect from light.

Standardization of 0.1 N Ferrous Ammonium Sulphate:

Take accurately 25 ml of 0.1 N Potassium dichromate in previously cooled mixture of 10 ml water and Sulphuric acid.Add 20 ml of distilled water than add two to three drops of Ferroin indicator solution. Titrate it with 0.1 N Ferrous Ammonium Sulphate Solution with constant stirring until the solution becomes brick colour. Repeat the above process in triplet set and note the reading.

CALCULATION  =     N1 x V1 = N x V2

Where,
                              N1= Normality of potassium dichromate
                                     V1= Volume potassium dichromate
                              N2= Unknown Normality of ferrous ammonium sulphate 
                              V2= Burette reading of ferrous ammonium sulphate 

Preparation of 0.1 N Ammonium thiocyanate:

Take Ammonium Thiocyanate A.R grade. Take about 8 gm of ammonium thiocyanate in beaker and add 50 ml of carbon dioxide free water. Dissolve it by stirring than add sufficient carbon dioxide free water to produce 1000 ml and mix well. Transfer the solution in reagent bottle and allow the solution to stand in tightly stopper bottle for 24 hours. After 24 hours standardize the solution then use for analysis.

NOTE: Store in a tightly stopper bottle and protect from light.

Standardization of 0.1 N Ammonium thiocyanate:


Take accurately 25 ml of  0.1 N silver nitrate in stoppered flask. Dilute it with 50 ml of water than add 2 ml of nitric acid and 2 ml of ferric ammonium sulphate solution. Titrate with the ammonium thiocyanate solution to the first appearance of a Red - brown colour becomes red colour.
Repeat the above process in triplet set and note the reading.

CALCULATION  =     N1 x V1 = N x V2

Where,
                              N1Normality of silver nitrate
                                     V1=  Volume of silver nitrate
                              N2= Unknown Normality of ammonium thiocyanate
                              V2= Burette reading of ammonium thiocyanate

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