Vinegar. In this investigation I am going to find out the concentration of ethanoic acid in vinegar. The concentration of acid is different in the product made by different manufactures. I will react the acid in the vinegar solution of sodium hydroxide o

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Naz Mariwan

Concentration of Vinegar

Introduction

In this investigation I am going to find out the concentration of ethanoic acid in vinegar.  The concentration of acid is different in the product made by different manufactures. I will react the acid in the vinegar solution of sodium hydroxide of known concentration in a titration experiment.

Equipment

  • Plastic beaker
  • Glass beaker
  • Pipette
  • Funnel
  • Phenolphthalein
  • Vinegar

Method:

  • Rinse the pipette with the diluted solution of vinegar.

  • Rinse the conical flask with distilled water Pipette 25cm³ of diluted vinegar solution to the conical flask and add 4-5 drops of the indicator.

  • Rinse the burette with the solution of Sodium Hydroxide and be sure to get rid of any air bubbles in the tip of the burette.

  • Using the filter funnel, carefully fill the burette with the solution of Sodium Hydroxide.

  • Record the initial burette reading in a results table.

  • Set up the burette and the conical flask in the corresponding places for the titration.

  • Make sure there are no bubbles in the burette before using it.

  • Slowly and carefully run Sodium Hydroxide solution from the burette into the conical flask with swirling.

  • Do this until the solution changes from colourless to light pink. This is the end-point.

  • Record your final burette reading also to the nearest 0.05 cm³.

  • Repeat this procedure until 2 concordant results are obtained making sure you rinses the conical flask between every titration.    

Accuracy

All burette readings must be recorded to the nearest 0.05 cm³ (1 drop). Consecutive titrations should be concordant. This means that they are either identical or within 0.10 cm³ of each other. The titration must be repeated until this is achieved. Burette readings must be recorded to 2 decimal places.   Results table for a titration:   Burette Rough 1st Accurate 2nd Accurate Final (cm³)       Initial (cm³)       Titre (cm³)           Titre: final burette reading – initial burette reading

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We know that NaOH is in a one to one reaction with the Ethanoic acid:

NaOH + CH3COOH → CH3COONa + H2O

Safety

For safety, these rules should be followed: Wear safety goggles at all times. Make sure there is good ventilation as some solutions have strong smells. Sodium Hydroxide is corrosive and Hydrochloric Acid is irritants so wash your hands thoroughly if there is any contact with the chemicals.

 

  • Thermometers contain mercury which is poisonous so be careful not to break it.
  • Handle all glassware with care as they may be ...

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