There is one type of quantitative analysis used which is Titration. The experiment which I am undertaking is finding out the volume of HCL needed to neutralise (1 mol dm -3) NaOH. I will then make a brief record on the results.

Jetesh Kerai 10T

Introduction:

Safety Points:

Do not play around when doing the experiment.

Never run in the laboratory.
Avoid contact with chemicals used.

Never smell dangerous chemicals.

Never leave bottles open.
Always wear a pair of safety goggles.

Materials:

Pair of Safety goggles
Phenolphalein indicator
Sodium Hydroxide Solution (1 mol dm -3)
Clamp
Stand
Graduated pipette
Conical flask
Burette
Hydrochloric acid

Method:

I rinsed out a 25 cm3 graduated pipette with sodium hydroxide solution (1 mol dm-3).

I used a pipette to measure out 25 cm3 of sodium hydroxide solution (1 mol dm-3) using a graduated pipette (with pipette filter) into a 250cm conical flask that had been rinsed out with distilled water.

I added 3-4 drops of Phenolphalein indicator.

I held the burette in a clamp and stand, I washed a burette twice with a few cm of the hydrochloric acid whose concentration had to be found.

I cautiously poured the (1 mol dm-3) of hydrochloric acid being cautious by bringing the burette down to my eye level and used a filter funnel lifted slightly from the top of the burette to allow air to escape.

I filled the burette to about 1cm above the 0 cm mark then ran a little through the tap until the level was on 0. ...

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I added 3-4 drops of Phenolphalein indicator.

I held the burette in a clamp and stand, I washed a burette twice with a few cm of the hydrochloric acid whose concentration had to be found.

I cautiously poured the (1 mol dm-3) of hydrochloric acid being cautious by bringing the burette down to my eye level and used a filter funnel lifted slightly from the top of the burette to allow air to escape.

I filled the burette to about 1cm above the 0 cm mark then ran a little through the tap until the level was on 0. If the level fell below this then I would have had to record the precise volume to the nearest 0.05 cm.

I titrated it slowly with the NaOH solution constantly stirring and adding 2-3 drops at a time.

When the acid began to change colour I added the acid 1 drop at a time.

When the liquid became clear I stopped adding the hydrochloric acid and recorded the volume to the nearest 0.05cm.

I repeated the process three times until I had three recordings. If the solution turned yellow then I would have added too much acid. I would then have to retitrate it by using a graduated pipette and adding 1 drop of hydrochloric acid at a time.
The tricky part was adding the acid, because I had to stir the solution every time I added few drops of hydrochloric acid.

Evaluation:

One crisis which I came across was that I had to repeat the process to get an accurate reading. The burette was very accurate when I was adding the hydrochloric acid. One error always occurred was that the air bubbles where getting trapped, due to this I couldn’t get the right volume. The method may possibly have been done well if I had more time and possibly better and expensive equipment. The experiment was a success after the fourth try. I had a bit of problem with the technique, but my experienced science teacher helped me out. I found out the experiment was quite easy when my teacher introduced it to me.

Table of result:

The amount of HCL needed to neutralise NaOH was nearly 1 mol dm-3 of hydrochloric acid.

Discussion of vocational implications:

Electrochemical Techniques:

When a positive and a negative electrode are placed in a solution containing ions, and an electric potential is applied to the electrodes, the positively charged ions (cations) move toward the negative electrode, or cathode, and the negatively charged ions (anions) to the positive electrode, or anode. As a result, electric current flows between the electrodes. The strength of the current depends on the electric potential between the electrodes and the concentration of ions in the solution. Therefore, this instrumental quantitative method, called conductometry, is often used to measure the ion concentration in a solution.

In a related technique, electrodes specially constructed to accept only specific ions are used to determine the sodium ion or calcium ion concentration or the pH of the solution being analyzed. This is different from my method because I didn’t have time to do the electrochemical technique and didn’t have the correct equipment for it. So therefore I used a rapid and accurate technique to get my results.

Safety features used in industries: