Experiment -2

Name of the Experiment: Standardization of Hydrochloric acid (HCl) solution by the Standard Sodium Carbonate (Na₂CO₃).

Some Basic Definition :

Volumetric Analysis : Volumetric analysis is a quantitative analytical method. It is a method in which the amount of a substance is determined by measuring the volume that it occupies and the volume of a second substance that combines with the first in known proportions. This is also called titrimetric analysis or titration.

Titrant : The reagent of known concentration is called the titrant

Titrand: The substance being titrated is termed the titrand.

Indicator : Indicator are substance which indicate the end point of a titration by change of colour.

End – point : The point at which the reaction is completed bu titration process is called end –point.

Neutralization Reaction :

A neutralization reaction is when an acid and a base react to form water and a salt and involves the combination of H⁺ ions and OH^- ions to generate water. The neutralization of a strong acid and strong base has a pH equal to 7. The neutralization of a strong acid and weak base will have a pH of less than 7, and conversely, the resulting pH when a strong base neutralizes a weak acid will be greater than 7.

Principle:

In Solution Sodium Carbonate (Na₂CO₃) is weak base and Hydrochloric acid (HCl) is strong acid. Besides that Na₂CO₃ is Primary standard and HCl acid is secondary standard substance. So if HCl is added in the standard Na₂CO₃solution, the reaction will be happened

Na₂CO₃ + 2HCl = 2NaCl + CO₂+ H₂O

For complete titration one mole of sodium carbonate two mole of HCl are required.That is the equivalent weight of sodium carbonate is half of its molecular weight.From the weight of sodium carbonate is taken to make the solution to Normal solution.We can calculate the solution to normality.If V₁ is the volume of the standard solution which strength is S₁ and required to complete titration of V₂ ml of the other solution and the strength S₂

Then V₁S₁ =V₂S₂

Or,S₂ = V₁S_{1 /}V₂

The value of S₂ may be calculated if the other three quantities are known.

Since HCl Solution has to standard by the standard Sodium Carbonate solution. So firstly have to prepare standard Na2CO3 solution.

Apparatus: Digital balance, Measuring Flask, Wash bottle, Conical Flask, Pipette, Burette, Stand and Cramps.

Chemical: Sodium Carbonate (Na₂CO₃) , Hydrochloric acid (HCl),Methyl Orange, Distilled water.

Preparation of Sodium Carbonate (Na₂CO₃) :

I wanted to prepare 100 ml of 0.1N Solution. So, we can Calculate like this way.

Molecular weight of Na₂CO₃ = 23*2+12+16*3 =106

Equivalent weight of Na₂CO₃ = 106/2 = 53

So In 1000ml of 1N Na₂CO₃ present = 53g

1 1N =53/1000g

100 0.1N =(53*100*0.1)/1000g = 0.53 g

Concentration of Na₂CO₃ = wt taken /wt to be taken X desired conc.

= 0.53 / 0.53 X 0.1 N

= 0.1 N

Standardization of HCl solution

Procedure:

1. By taking weight 0.53 g of Na₂CO₃transferred to 100ml measuring flask. Dissolved it in distilled water and made up to the mark. Shake well and mixed thoroughly.

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 washed with distilled water and then rinsed with Na₂CO₃ solution.

4. Took 10ml solution of Na2CO3in 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 methyl orange 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 Carbonate solution and continuously rotated the conical flask. But not touch with the tip of burette.

10. Add slowly until the solution comes yellow to light pink colors. 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 Carbonate solution.

13. The Procedure is repeated three or four times

Calculation:

We know, V₁S₁ =V₂S₂ Here,V₁ =Volume of Sodium Carbonate

Or, S₂ = V₁S_{1 /}V₂ S₁ =Concentration of Na₂CO₃ solution

V₂ =Volume of HCl

S₂ = Concentration of HCl

Result :

Concentration of HCL solution …………….. N