CP3

Neutralisation reaction

Sodium hydroxide

Methyl orange

Yellow to red

It changes colour sharply at the pH of the equivalence point for a strong acid-strong base titration

Pipette

To avoid direct mouth contact and ensure safety

Burette

It allows easy swirling without spillage

Rinse the burette with hydrochloric acid

To avoid altering the concentration of the reactants

To get an approximate value for the end point

Repeat until two concordant results are obtained

Two results within 0.1 cm³ of each other

To help observe the colour change clearly

To avoid parallax error

The volume of acid required to neutralise the alkali

To avoid overshooting the end point

Wear eye protection and gloves

Exclude them from the mean titre calculation

1-Wash out a 250 cm³ volumetric flask with distilled water

2-Use the pipette to add 25 cm³ hydrochloric acid in to the volumetric flask and make the rest up with distilled water

3-Pour a 25 cm³ sample of the HCl solution in to the conical flask and add a few drops of phenolphthalein indicator

4-Prepare your apparatus for the titration – sodium hydroxide in the burette and the hydrochloric acid in the conical flask

5-Titrate the contents of the flask against the NaOH solution and record the titre to the nearest 0.05 cm³ (when a permanent pink colour appears)

6-Conduct additional titrations until you have concordant values