Performing a Titration

Specification Point 3.18:
  • Describe how to carry out an acid-alkali titration, using a burette, pipette and a suitable indicator, to prepare a pure, dry salt.

Aim: 

  • To investigate the preparation of a pure, dry salt by titration

Salt by Titration, Edexcel GCSE Chemistry

Diagram showing the apparatus needed to prepare a salt by titration

Materials:

  • Hydrochloric acid, sodium hydroxide solution, goggles and lab coat
  • Suitable indicator (methyl orange or phenolphthalein), teat pipette
  • Conical flask, burette, stand, volumetric pipette

Method:

  • Use the pipette to measure the alkali into a conical flask and add a few drops of indicator.
  • Add the acid into the burette and note the starting volume.
  • Add the acid very slowly to the conical flask until the indicator changes colour.
  • Note and record the final volume of acid in burette and calculate the volume of acid added.
  • Repeat the procedure with the same volume of acid and alkali but without the indicator.
  • Heat gently to partially evaporate the water, leaving a saturated solution.
  • Leave in a dry place so the remaining water evaporates, allowing crystallisation to occur.
  • This may take a few days depending on ambient conditions.

Analysis of results:

  • After a few days record the appearance of the NaCl crystals to include a diagram and/or photograph.
  • In particular comment on their colour and shape.

Conclusion:

  • The titration method is used when the salt product is soluble, hence there is no need to filter any insoluble materials.
  • The indicator is used to identity the amount of acid needed for neutralisation and is not used in successive titrations to avoid contamination of the product.
  • Evaporation of the water leaves the desired pure salt.

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Edexcel GCSE Chemistry Notes

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Morgan Curtin Chemistry

Author: Morgan

Morgan’s passion for the Periodic Table begun on his 10th birthday when he received his first Chemistry set. After studying the subject at university he went on to become a fully fledged Chemistry teacher, and now works in an international school in Madrid! In his spare time he helps create our fantastic resources to help you ace your exams.