Acid-base titration

• Why do you need to remove funnel before you start a titration?

  So then there wont be any tiny drops that would affect the practical.
• Why would you rinse the inside of a conical flask with a small amount of distilled water and why won't it affect the final titre?

  • To make sure all the reactants have reacted
  • And the distilled water wouldn't react with any of the HCl or sodium hydroxide so it won't affect practical.
• Why should you drop only a couple of drops of indicator?

  Since it would take longer to see the colour change which would affect the pratical
• Why do we use conical flask instead of beakers?


  To prevent splashes which means the whole reactants reacts with the practical
• The student identified use of the burette as the largest source of uncertainty in the experiment. Using the same apparatus, suggest how the procedure could be improved to reduce the percentage uncertainty in using the burette. Justify your suggested improvement.

  Using more mass of the solid would mean a larger volume of HCL would be needed which would decrease the uncertainty
• Preparing a 250cm3 volumetric flask of unknow group 2 carbonate (MCO3 )

  • First using a spatula measure out 1.30-1.40 g of MCO3 into a weighing boat using a balance. Measure and record mass of weighing boat and metal carbonate.
  • After rinsing the pipette with 1.00 moldm-3 of HCl and using the pipette and filler measure out 50cm3 of the acid into a beaker
  • Transfer solid metal carbonate into beaker and swirl with a glass rod.
  • Measure and record the mass of the weighing boat and compare the difference with 1st measurement to find the mass of metal carbonate used
• Preparing a 250cm3 volumetric flask of unknow group 2 carbonate (MCO3 ) pt2

  1. When effervescence stops, transfer the solution into a 250cm3 volumetric flask using a funnel
  2. Using distilled water rinse the beaker, glass rod and funnel into the flask and fill the flask with distilled water up to the 250cm3 mark
  3. Put a stopper on the flask and invert it to ensure its mixed
• What equipment is used to carry out a titration?

  Pipette, pipette filler, and burette
• What is the purpose of a pipette in a titration?

  To accurately measure the volume of a reactant
• How does a pipette filler assist in using a pipette?

  It helps to draw liquid into the pipette safely
• How to do a Titration

  1. Set up a clamp stand and clamp the burette
  2. Rinse out the burette with the NaOH and then fill the burette with the NaOH using a funnel. Then remove funnel and open the burette just to make sure there's no air space
  3. Record the initial burette reading
  4. Using a pipette and a pipette filler, rinse the pipette with HCl acid and transfer 25cm3 of the acid into a conical flask
• How to do a titration pt2

  1. Add 3 drops of an indicator to the conical flask e.g. phenolphthalein
  2. Add the NaOH from the burette into the conical flask until solution turns pink
  3. Record final burette reading as the rough
  4. Rinse conical flask with distilled water
  5. Repeat steps 2-7 until results are concordant (0.1 ) but for step 6 when you get knew the end point add a few drops at a time to get the lightest colour of pink