Chem IA 2

Introduction: In this reaction the titration reaction; in this five antacids will be titrated. These antacids are used in medicines to neutralise the acidity present in the stomach. With the aid of this experiment we will check the ability of these 5 antacids to neutralise an acid of known strength. A solution of Hydrochloric acid (1.5 pH) also called Gastric juice is present in the stomach. Gastric juice is important for the process of digestion, however, if the acid is concentrated, it may irritate the lining of the stomach and result in causing tenderness. This may result to the symptoms of heart burns which can in turn lead to stomach ulcer. To prevent this, one consumes Antacids tablets. Research Question: Determine the volume of hydrochloric acid which can be neutralized by the given samples of commercial antacids and compare their effectiveness. Hypothesis: In the experiment out of all the 05 antacids used, Digene is one of the most commonly used antacids by people and mostly prescribed by the doctors, therefore I hypothesize that is should be the most effective in neutralizing HCl. Dependent Variable: For standardisation titrations: The volume of HCl measured by the difference of final and initial in the burette readings. For antacids titrations: Volume of NaOH solution used to complete neutralization of the solution and HCl. Independent Variable: For standardisation titrations: The volume of NaOH and Na2CO3 used for titration of standardisation of HCl and NaOH respectively. For antacid titrations: The amount of HCl in which 2.00 gm of the antacids is dissolved it. Controlled Variables:

       

The strength and total volume of HCl used for the experiment. The time required for the solution of antacids powder and HCl is left stationary before titration. The volume of antacid and HCl used in titration flask. Na2CO3’s total strength and volume used for titration. The volume of Na2CO3 used in the titration flask for the standardisation on HCl. The volume of NaOH used in the titration flask to perform the standardisation of NaOH. The volume and strength used for NaOH solution in the experiment. Temperature at which different titrations were carried out.

Method to control variables: Dependent Variable: The volume of NaOH used to neutralise completely the solution of antacid prepared and HCl will give us the effect resulting in neutralising HCl, it will be further measure in a burette and will wait for the colour change to pink. Hence, the colour changes marks the presence of an indication and changes it colour at the end of the reaction. Just like this we will measure the initial and final burette readings to record the observations made for HCl. Similarly, we will measure the volume of HCl solution by using different initial and final burette readings.

Independent variable: 1. The volume of HCl in which the antacid will be dissolved affects the end point of the reaction, hence to keep it controlled the exact mass of 2gm of antacid will be weighed on an electronic weighing machine and will be dissolved in 150 ml of HCl. The volume will be measured by the help of a measuring cylinder. To perform the standardization titration will use 20 ml pipette and transfer the solutions into titration flasks to get accurate volumes. 2. In the same way, the volume of NaOH and Na2CO3 used in the titration flask for standardisation of HCl and NaOH

Controlled Variables: i.

The strength of HCl used for the experiment should remain the same to get consistence readings while doing titration. For this I will add 5.6ml of concentrated HCl in 2lof distilled water to get a HCl of strength

ii.

iii.

iv.

.this 2l of solution will be used for the entire

experiment. The time for which all the antacids solutions and HCl is kept stationary for one hour, this is done for dissolution of all different antacids. The volume of solution and HCl used in titration should be kept constant will be later used for comparison of effectiveness of the 5 antacid which will be neutralised in acid of 20 ml of this solution and will be accurately measured with a pipette. The strength of Na2 CO3 used for different titrations will be kept constant throughout. To get standardisations and effectiveness of comparisons and to neutralise HCl acid 1.77 gm of anhydrous sodium carbonate will then be dissolved in 500 ml of distilled water so as to get strength of

v.

vi.

vii.

⁄

.

The volume of solution of sodium carbonate used in the titration flask for the standardisation of HCl will be 20 ml. This will be done accurately by the help of pipette. The strength of NaOH for different titrations will be kept constant so as to avoid the problem of significant figures in result of 10.67 gm of NaOH will be dissolved in about 4l of distilled water. The room temperature at which all the titrations is carried out is significant and affect the burette readings for titrations as this may affect the rate of reaction. Hence, the room temperature and air temperature should remain constant.

Apparatus Used:

Table of different apparatus used with their quantity and capacity: Table 1 : Apparatus Used Serial number

Apparatus Used

Capacity

Quantity

1.

Burette

50ml

1

2.

Clamp stand

-

1

3.

Pipette

20ml

1

4.

Conical flask

200ml

2

5.

Funnel

-

1

6.

Filter paper

-

8

7.

Beaker

250ml

2

8.

Beaker

50ml

1

9.

Measuring cylinder

200ml

1

10.

Measuring cylinder

1000ml

1

11.

Winchester jar

4l

1

12.

Winchester jar

3l

2

13.

Mortar

-

1

14.

Electronic weighing machine

-

1

15.

Stirrer

-

1

16.

Digital thermometer

-

1

17.

Watch glass

-

1

18.

Spatula

-

2

19.

Suction Pump

-

1

Chemicals Used: The following table consists of all the chemicals used with their concentrations and volume required. Table 2 Chemicals Used Serial Number:

Chemical:

Concentration:

Amount:

1.

Hydrochloric acid(S)

12 M

5.6 (

2.

Anhydrous Sodium Hydroxide

-

10.67

3.

Anhydrous Sodium carbonate

-

1.77 ( gm

4.

Distilled Water

-

8000.0 ( mL

(

Antacid Used: Table 3 Antacid Used Serial Number:

Antacid:

Mass used:

1.

Diegene

2.00gm

2.

Gelucil

2.00gm

3.

Divol

2.00gm

4.

Eno

2.00gm

5.

Digusil

2.00gm

mL

gm

Procedure:  Before beginning the experiment wash all the apparatus to be used with tap water. Preparation of I. II. III.

Measure exactly 5.6 ml of concentrated (12 M ) hydrochloric acid solution with the help of a measuring cylinder. Then dissolve this concentrated hydrochloric acid will be dissolved in 1L of distilled water. Store this solution in a Winchester jar and only this solution will be used whenever hydrochloric acid is used in the experiment.

Preparation of I. II.

III. IV. V.

II.

III. IV.

Sodium carbonate solution:

First weigh 1.77gm of anhydrous sodium chloride in a watch glass with the help on an electronic weighing machine. Then dissolve this anhydrous sodium carbonate in about 200 ml of distilled water in a beaker and then stir the solution till there are no visible crystals present in the beaker. After this pour this solution in a 500 ml measuring cylinder. Then pour distilled water in the measuring cylinder till the volume of solution reaches to 500 ml. Then transfer this solution in a 2 L Winchester jar.

Preparation I.

Hydrochloric solution:

sodium hydroxide solution:

Weigh 10.67 gm of solid sodium hydroxide in a watch glass on an electronic weighing machine. After this dissolve this solid sodium hydroxide solution in about 200ml of distilled water in a beaker and stir this solution till there is no visible solid sodium hydroxide. Then pour this solution in a measuring cylinder of capacity 1 L. After measuring it, pour this solution in a 4L capacity glass jar. After this pour 3L of measured distilled water in the same Winchester jar.

Titration for antacids test:

1. Take about 5-6 tablets of digene and crush them in mortar till there are only fine powder-like particles left. 2. Weigh this digene powder in a watch glass on an electronic weighing machine. First weigh empty watch glass and then weigh 2.00 gm of the antacid. 3. After weighing 2.00gm of antacid measure 150 ml of

hydrochloric

acid in a measuring cylinder and dissolve the antacid in this 150 ml of measured hydrochloric acid with the help of a stirrer. 4. Then leave this solution of antacid for about one hour. 5. After one hour filter this solution in a conical flask with the help of a funnel and filter paper. 6. Then fill the burette with

sodium hydroxide solution.

7. Note the initial burette reading. 8. Take 20 ml of antacid solution win a titration flask with the help of a pipette and pipette pump. 9. After this add a few drops of phenolphthalein in the titration flask. 10. Then begin titration by opening the valve of burette and allowing it to drop drop by drop in the titration flask. 11. Keep the valve open till a permanent pink colour is obtained. This will be the final burette reading. 12. Repeat the above steps with Gelusil, Divol, Eno and Digusil. Titration for the standardisation of hydrochloric acid: I. II. III. IV. V. VI. VII.

Start by filling the burette with hydrochloric acid and note the initial reading. Then take 20 ml of

sodium carbonate solution in titration flask with

the help of a 20ml pipette and pipette pump. Then add a few drop of methyl orange in the titration flask. Then begin titration and wait till a permanent light red colour is obtained from the previous colourless solution in the titration flask. This will be the final burette reading. The difference between final and initial burette reading will be the volume of hydrochloric acid used. Repeat this titration till three concordant readings are obtained.

Titration for the standardisation of sodium hydroxide:

I. II. III. IV.

V. VI.

First fill the burette with prepared hydrochloric acid and note the initial reading. Secondly take 20 ml of prepared sodium carbonate in the titration flask with the help of a 20 ml pipette and pipette pump. Next add a few drops of methyl orange which will act as indicator. Then start the titration and note the final burette reading as the drop at which a permanent light red colour is obtained from the previous orange colour in the titration flask. The difference between initial and final burette reading will be volume of hydrochloric acid used. Repeat this titration till three concordant readings are obtained.

Precaution and Safety:  Be careful while handling different acids as if they are spilled in the hand they might cause damage t the skin.  Make sure that the remaining acids after the experiment are disposed off properly and not just thrown away in usual garbage bin or pour in the sink as they are harmful for the environment.  Wear a lab coat and protective goggles while performing the experiment.  Be very carefully while handling the glass equipments and make sure that they put properly in a separate tray after usage.  Wear gloves for handling antacids.  Wash hands immediately after any acid is accidently fell on the hands.  Use pipette pump instead of using mouth to fill the pipette.