How to make primary standard sodium carbonate solution ?

Titration:

It is a method of finding the concentration of a solution by reacting it with a standard solution and
 measuring their corresponding volumes.

Standard solution:

A solution of accurately known concentration.

          **Preparing a standard solution:

250 cm³ , 0.1 moldm^-3 of Na₂CO₃ solution is to be made.

 Na₂CO₃ is a primary standard i.e. a pure , stable, soluble, solid compound. It’s mass can be measured 
and can be dissolve completely in water.

a) Apparatus required:

    1) Top pan balance 2) Weighing bottle 3) Beaker 4) Volumetric flask 5) Sodium Carbonate 
    6) Funnel  7) Distilled water 8) Stirrer/ Glass rod 9) Dropper.

b) First calculating the required mass of Na₂CO₃ to make the standard solution:

    No. of moles of Na₂CO₃ : (0.1X250X10^-3 ) moles    [No. of moles= Conc. in moldm^-3 X Volume in cm³ X 10^-3]

    Mass of Na₂CO₃ : (0.1X250X10^-3)X(46+60)              [ Mass= no. of moles X Molar Mass]

    Mass of Na₂CO₃ : 2.65g  is required for making a standard solution.

c) Procedure:

Step 1: - Accurately measuring the mass of the Na₂CO₃ solute in weighing bottle. 

             - Placing the empty weighing bottle on the top pan balance and reading it’s mass zero by pressing

               tare/ zero button.  

                   

             -Then taking reading of the mass of Na₂CO₃ by placing it over the weighing bottle on the

               top pan balance.

                   

Step 2: - Transferring Na₂CO₃ to beaker by using distilled water.

            - Transferring Na₂CO₃ solute to the beaker by washing Na₂CO₃ from weighing bottle with  

               distilled water. Making sure that every little bit of Na₂CO₃ is washed down to the beaker with

               distilled water.

                      

                    

Step 3: - Dissolving all of the Na₂CO₃ in distilled water by using stirrer/ glass rod in beaker.  

                 

Step 4: - Taking a volumetric flask of 250 cm³ and placing a funnel on top opening of

                volumetric flask.

                   

                 

             

             - Now transferring Na₂CO₃ solution to the volumetric flask. Pouring Na₂CO₃ along the side of 

               the glass stirrer to avoid spillages. Slowly transferring all the solution from beaker to the

               volumetric flask.

          

Step 5 :- Now rinsing the glass rod with distill water to the volumetric flask.

The beaker and the funnel is rinsed thoroughly with distilled water and washing of stem of the volumetric flask is allowed to run down into the flask.Carrying out this step carefully since this is the most essential step.

Now rinsing the glass rod with distill water to the volumetric flask.

The beaker is rinsed thoroughly with distilled water.

Pouring the solution of Sodium Carbonate into the volumetric flask.

The funnel is rinsed thoroughly with distilled water and washing of stem of the volumetric flask is allowed to run down into the flask.

Step 6:- Now carefully bringing the lower meniscus close to the graduation mark on the volumetric flask by giving distilled water. Stopping at about 1 cm³ away from the graduation mark.

Then carefully bringing lower meniscus to the graduation mark by adding distilled water drop wise with the help of dropper. Eyes should be level with graduation mark.

Step 7: - A stopper is placed over the volumetric flask and inverted several times to ensure homogeneous(uniform) solution in volumetric flask which is very essential while carrying out titration.

Shaking, swirling the volumetric flask won’t help to make homogeneous solution because of the shape of the volumetric flask.

 Then labeling the flask containing the primary standard solution of Na₂CO₃.

   

Precaution:

1) Wear gloves 

2) Eye protective gear. 

3) Solute shouldn't get loss while transferring from weighing bottle.
4) Solution shouldn't spill from beaker while transferring to volumetric flask.
5) Rinsing every pieces of apparatus with distilled water is essential and pour that solution to volumetric flask   

carefully.
6) Eye level should be exactly perpendicular to the graduation mark of the volumetric flask.perpendicular to the graduation mark.