Titrations class XI

EXPERIMENT NO.     ------

AIM :   To determine the normality & strength of given HCl solution by titrating it 

             against  N/ 10 Na2 CO3  solution.

APPARATUS REQUIRED :    Standard N/10 Na2 CO3  solution, funnel , burette ,   

    pipette, Methyl orange indicator ,test tube, conical  flask , beakers .

THEORY :  The reaction between  Na2 CO3  & HCl is neutralization reaction where 

                    Na2 CO3  is a salt of weak acid & strong base.

REACTION INVOLVED :

            Na2CO3  (aq) +  HCl (aq)   ----------------------→ 2 NaCl (aq)  + H2O (l) + CO2 (g)

PROCEDURE : 

    1. Wash the burette with water & rinse it with the given Na2 CO3  solution.

   2. Fill the burette with Na2 CO3  solution & clamp it. Note down the initial  

       reading of the burette ( Lower meniscus ).

   3. Wash the pipette with water & pipette out 10 ml  of HCl solution in the   

       conical flask & add 2-3 drops of Methyl orange indicator to it.

 4.  Run down the solution from the burette to the conical flask till the colour of    

       the solution changes from  pink to yellow.

10. Note down the final reading of the burette. Find out the volume of  Na2 CO3   

      used by subtracting initial reading  from the final reading of the burette.

11. Repeat the experiment to get the concordant readings.

OBSERVATION TABLE :

S. No.	Volume of  HCl solution (ml)	Initial reading of the burette        (ml)	Final reading of the burette      (ml)	Volume of Na2CO3 used        (ml)
1	10	0.0
2	10
3	10
4	10

CONCORDANT READING   = -----------

CALCULATIONS  :

       N  HCl X  VHCl     =     N Na2CO3  X  V Na2CO3      

       N Na2CO3  X V Na2CO3      

                        N HCl   =---------------------------------------

                                                         10

Strength of HCl  solution = N HCl X   Eq. mass of HCl  ( i.e. 36.5 g)

                                                          = _____ g/L

RESULT :   The Normality & Strength of the given HCl solution is  _______

                       &  _______   respectively.

PRECAUTIONS :

1. There should be no air bubbles in the burette.
2. Solution from the burette should be added in drops & should not run too fast.
3. Always read the upper meniscus in the case of coloured solution & lower in the case of colourless.
4. Titration flask should not be rinsed every time .

----—------—----------------------------------—-----------

DATE :                                                                                                                                                 

                                             EXPERIMENT NO.     ------

AIM :   To determine the normality & strength of given HCl solution by titrating it   against N/ 10 NaOH solution.

APPARATUS REQUIRED :    Standard N/10 NaOH solution,funnel , burette ,   

                                                     pipette, Phenolphthalein indicator ,test tube, 

              conical  flask , beakers .

THEORY :  The reaction between NaOH & HCl is neutralization reaction. It is an   Acid-Base titration.

REACTION INVOLVED

 NaOH (aq) +  HCl (aq) ----------→ NaCl (aq)  + H2O (l)

PROCEDURE : 

    1. Wash the burette with water & rinse it with the given NaOH  solution.

   2. Fill the burette with NaOH solution & clamp it. Note down the initial reading 

        of the burette ( Lower meniscus ).

   3. Wash the pipette with water & pipette out 10 ml  of HCl solution in the   

       conical flask & add 2-3 drops of phenolphthalein indicator to it.

 4.  Run down the solution from the burette to the conical flask till the colour of    

       the solution changes to light pink.

10. Note down the final reading of the burette. Find out the volume of NaOH 

      used by subtracting initial reading  from the final reading of the burette.

11. Repeat the experiment to get the concordant readings.

OBSERVATION TABLE :

S. No.	Volume of  HCl solution (ml)	Initial reading of the burette        (ml)	Final reading of the burette      (ml)	Volume of NaOH used        (ml)
1	10	0.0
2	10
3	10
4	10

CONCORDANT READING   = -----------

CALCULATIONS (b) :

N HCl X  V HCl  = N NaOH X  l  VNaOH                                              

                             

       N NaOH X  V NaOH 

                    N HCl =          -----------------------

                                                  V HCl 

  Strength of HCl  solution = eq.wt of HCl   X N HCl

.                                                                     = ---------------------------- g/L

                                                          .              

RESULT :  The normality & strength   of given HCl solution are -------- & 

                    -------------- respectively. 

                     

PRECAUTIONS :

• There should be no air bubbles in the burette.
• Solution from the burette should be added in drops & should not run too fast.
• Always read the upper meniscus in the case of coloured solution & lower in the case of colourless.
• Titration flask should not be rinsed every time .