Titration required practical

• Objective:

  To determine the reacting volumes of a strong acid and a strong alkali by titration
• Hypothesis:

  The titration method can be used to calculate the concentration of an acid
• Materials:

  • 25 cm3 volumetric pipette
  • Pipette filler
  • 50 cm3 burette
  • 250 cm3 conical flask
  • Small funnel
  • 0.1 mol/dm3 sodium hydroxide solution
  • Sulfuric acid – concentration unknown
  • Phenolphthalein indicator
  • Clamp stand, clamp & white tile

  
• Use a funnel to fill the burette but be sure to remove it before starting the practical as it can drip liquid into the burette, making the initial reading false.
• Method

  1. Use the pipette and pipette filler and place exactly 25 cm3 sodium hydroxide solution into the conical flask
• Method 


  2.

  1. Place the conical flask on a white tile so the tip of the burette is inside the flask
• Method 


  3.

  1. Add a few drops of a suitable indicator to the solution in the conical flask
• Method 


  4.

  1. Perform a rough titration by taking the burette reading and running in the solution in 1 – 3 cm3 portions, while swirling the flask vigorously
• Method 


  5.

  1. Quickly close the tap when the end-point is reached (sharp colour change) and record the volume, placing your eye level with the meniscus
• Method 


  6

  1. Now repeat the titration with a fresh batch of sodium hydroxide
• Method 


  7

  1. As the rough end-point volume is approached, add the solution from the burette one drop at a time until the indicator just changes colour
• Method 


  8

  1. Record the volume to the nearest 0.05cm3
• Method 


  9

  1. Repeat until you achieve two concordant results (two results that are within 0.1cm3 of each other) to increase accuracy
• Method 


  10. Record results in table

  
• The mean titre is calculated and used to calculate the concentration of the acid in mol/dm3, ignoring any anomalous results