Titration

• Aim of practical is to find concentration or the volume of acid needed to neutralise an alkali.
• Method to find volume of acid; (part 1)

  1. Firstly, using a pipette measure 25cm^3 of the alkali into the conical flask and place on white tile.
  2. Secondly, fill the burette with acid using a funnel and record the intial reading in the burette (making sure to take reading from the bottom of the meniscus).
  3. Thirdly, add 5 drops of an indicator (phenolphthalein) to conical flask.
  4. Next, open the burette tap and continuously swirl the concial flask, and near the end add the acid drop-by-drop. During this the colour will start to change slightly.
• Method to find volume of acid; (part2)

  5. Then, close the burette when there is a permanent colour change happens to the phenolphthalein.

  6. Finally, record the final reading of the acid in the burette, and calculate the titre.

  7. Repeat practical and calculate mean titre.
• Method to find concentration of acid; (part 1)

  1. Firstly, using a pipette measure 25cm^3 of the alkali into the conical flask and place on white tile.
  2. Secondly, fill the burette with acid using a funnel and record the intial reading in the burette (making sure to take reading from the bottom of the meniscus).
  3. Thirdly, add 5 drops of an indicator (phenolphthalein) to conical flask.
  4. Next, open the burette tap and continuously swirl the concial flask, and near the end add the acid drop-by-drop. During this the colour will start to change slightly.
• Method to find concentration of acid; (part 2)

  5. Then, close the burette when there is a permanent colour change happens to the phenolphthalein.

  6.Finally, record the final reading of the acid in the burette, and calculate the titre.

  7. Repeat practical and calculate mean titre.

  8. Then work out the concentration by; calculating number of moles in alkali, balance equation, use ratio to find moles for acid, use moles/volume (the titre) to work out concentration.
• Different indicators can be used, such as phenolphthalien or methyl orange.
• Titration set up;

  A) pipette

  B) burette

  C) conical flask

  D) white tile

  
• Colour of phenolphthalein in Acid = colourless and in Alkali = pink.
• To convert concentration of acid from mol/dm^3 to g/dm^3, you have to multiply by molar mass of the acid.