Principle: In solution NaOH is strong base and HCl is strong acid. Besides that both of them are secondary standard substance. In this experiment, HCl will be given standardization. So have to find out the strength of NaOH solution. In titration the reaction will be happen.
NaOH + HCl = NaCl + H2O
For complete titration one mole of sodium hydroxide and one mole hydrochloric acids are required. So the equivalent weight of NaOH is equal to its molecular weight. From the weight of the sodium hydroxide is taken to make the solution Normality. If V1 is the volume of the standard solution and its strength is S1 which is required for complete titration, other volume of the solution is V2 and its strength is S2
Then V1S1 = V2S2
Or,S2 = V1S1 / V2
This value of S2 may be calculated if the other three quantities are known.
Apparatus: Digital balance, Measuring Flask, Wash bottle, Conical Flask, Pipette Burette, Stand and Cramps.
Chemical: Sodium hydroxide (NaOH), Hydrochloric acid (HCl), phenolphthalein , Distilled water.
Preparation of NaOH approximate solution: Since NaOH is secondary standard substance. So after preparing the solution,this solution will be approximate solution. I wanted to prepare 100ml of 0.1N solution. So I calculate like this way.
Molecular weight of NaOH = 23 + 16 +1=40
Equivalent weight = Molecular weight =40
In 1000ml solution 1N NaOH present =40 g
100ml “ 0.1N “ “ =40*100*0.1/1000 g
=0.4 g
Procedure: 1.We took 0.4 g NaOH and Transferred to 100ml measuring flask.It was dissolved it with distilled water. Shake the mixture so that the solute mixed completely. The solution made up to the mark.
2. We took clean burette rinsed and then filled it with HCl solution. Then, the burette was stood by stand and cramps.
3. We took a pipette of 10ml which was cleaned and washed with distilled water and then rinsed with NaOH solution.
4. Took 10ml solution of NaOH in a conical flask from the measuring flask(Beaker if the solution pour in the beaker)with the help of an appropriate pipette.
5. Diluted with a little of water and drop 1 to 2 drops phenolphthalein indicator.
6. Then, we placed the flask upon a white paper under the burette tip.
7. Place the burette such way that its tip 1 inch up from the mouth of the conical flask. But not touch it.
8. Noted the burette reading.
9. Slowly run the acid solution into the sodium hydroxide solution and continuously rotated the conical flask. But not touch with the tip of burette.
10. Add slowly until the solution comes light pink colors to colorless. This is the end point of the titration.
11. Noted the burette reading in the data table.
12. The difference between the initial and final burette reading gives the volume of the acid solution required to completely neutralize y ml (10ml) sodium hydroxide solution.
13. The Procedure is repeated three or four times
Table: Determination volume of HCl
Calculation: We know, V1S1 =V2S2 Here,V1 = Volume of HCl
Or, S2 = V1S1 /V2 S1 =Concentration of HCl solution
V2 =Volume of NaOH,
S2 = Conc. of NaOH =?
Result : Concentration of NaOH solution ……………..