RP 1: making a volumetric solution

• Method for making solution:

  1. Weigh the sample bottle containing the solid on a (2dp) balance
  2. Transfer solid to beaker and reweigh sample bottle
  3. Record the difference in mass
  4. Add distilled water and stir with a glass rod until all the solid has dissolved
  5. Transfer to a volumetric flask with washings
  6. Make up to the 250cm^3 mark with distilled water
  7. Shake flask
• Reducing uncertainties:

  • use more accurate balance
  • use larger mass
• Errors:

  fill so the bottom so the meniscus sits on the line on the neck of the flask
• Concordant- within 0.1cm^3
• Safety precautions: acids and alkalis are corrosive, so wear gloves and eye protection
• Reducing uncertainties in titration:

  • use apparatus with lower apparatus uncertainty
  • titre volume needs to be made larger by increasing the volume and concentration of the substance in the conical flask
• Weighing by difference ensures more accurate measurement of mass added
• Rinse burette before use with small volume of solution
• Ensure jet space in burette is filled and doesn't contain air bubbles
• Carry out a simple acid-base titration


  1. Pour standard solution into beaker

  2. Fill burette with standard solution

  3. Pour solution with unknown concentration into beaker

  4. Transfer 25cm3 of unknown solution to conical flask

  5. Add indicator

  6. Record initial burette reading

  7. Titrate until colour change

  8. Record final burette reading

  9. Repeat until concordant results
• Titration


  • Conical flask used to easily swirl mixture
  • Only a few drops of indicator required
  • Read burette to appropriate precision from bottom of meniscus
  • Add solution slowly, swirling gently near end-point
  • Use white tile to observe colour change
• Distilled water can be used to wash sides of flask during titration without affecting results
• Reducing uncertainties in a titration

  • Use pipettes/burettes with lower apparatus uncertainty
  • Increase titre volume by increasing volume/concentration in conical flask or decreasing concentration in burette
  • Don't leave NaOH in burette as it can damage apparatus