To determine the concentration of a sodium carbonate solution

Alkali : Acid

        1 :  2

   0.05 :  x

   0.05 :  0.10

Water : Acid

     24  :  1

Equipment, apparatus and chemicals

The amounts of solutions needed on:-

• 20cm³ of 2.5 moles of Hydrochloric acid
• 480cm³ of distilled water
• 250cm³ of Sodium Carbonate
• Methyl orange Indicator(which is red in acid and yellow in alkali)

 The apparatus needed for dilution of the acid:-

• Labels- so we can tell which beaker contains what.
• 2x        Beakers- to hold the acid.
• 1x 10cm³ pipette - to pipette the acid with.
• 1x Filter funnel – to pour the dilute hydrochloric acid through.
• 1x Standard flask- to hold 250cm³ of solution
• 1x Dropping pipette- to put water in and drop it in to the standard flask if needed.
• 1x Safety glasses- to protect eyes (from chemicals etc).

 The apparatus needed for the titration:-

• Labels- so we can tell which beaker or flasks contains what.
• 1x      Burette- so to measure the acid drop by drop how much is used.
• 1x     Burette stand- this is to hold the burette in place.
• 2x 25cm³ Labels- to measure 25cm³ of acid and alkali.
• 2x Pipette filler- to fill the pipette with solution.
• 1x White tile
• 4x     Conical- to contain 25cm³ of Na CO each for repeated titrations.
• 2x        Beakers- to hold the acid and the alkali.
• Methyl orange Indicator– So I am able to see the colour change clearly.
• 1x Safety glasses- to protect eyes (from chemicals etc).

Method

The dilution of Hydrochloric acid

1. Measure out 10cm³ of (2.5 molar) Hydrochloric acid. Using a filter funnel carefully transfer the solution into a 250cm³ standard flask.

2. If needed add distilled water until the level is close to the mark on the neck of the flask.

3. Remove the filter funnel and using a dropping pipette add enough water to bring the bottom of the meniscus up to the mark.

4. Invert the flask several times to help the contents mix the contents (e.g. label it Dilute Hydrochloric acid), If someone is doing a similar experiment label it with your name.

The Titration

1. Fill the burette with the 0.10 mol dm³ hydrochloric acid.

2. Pipette 25.0cm³ of the Sodium Carbonate solution into a conical flask add 4 drops of methyl orange.

3. Repeat the titration accurately until you have at least three concordant results.

4. Make a results table and calculate the mean titre, making sure you have indicated a volume.

Safety Precautions

A 2.5 mole solution of Hydrochloric acid and a solution of Sodium carbonate are harmful to the skin. If it comes in contact with the skin, wash the area with plenty of water under the supervision of a teacher. If it comes in contact with the eyes, flood the eyes flood the eyes with running water for as long as it takes for medical help to arrive. Eye Protection must be worn at all times.

I will take these precautions to make it a Fair test

1. I will take 3 concordant results
2. I will use the exact same apparatus for each experiment
3. Making sure that the apparatus is clean and free from contamination or residue
4. I will use the acid solution diluted so there should be no variation, instead of making a fresh batch each time
5. And The results will be recorded to 2 decimal places

Sources

• Class Sheets