Preparation and Standardisation of Solutions Using Titration

Preparation and Standardisation of Solutions Using Titration

Section 1: Understanding Titration

  • Titration: A quantitative laboratory method used to determine the concentration of an unknown solution (analyte) by reacting it with a standard solution (titrant).
  • Burettes: Precision instruments used in titration to measure out the titrant. They can discharge liquid in tiny, precise amounts.
  • Indicators: Substances that change colour at the end point of a titration. They are chosen depending on the reaction type and pH change.

Section 2: Preparing a Standard Solution

  • Standard Solution: A solution of known concentration, often used as the titrant. It’s prepared by dissolving a calculated amount of solute in a known volume of solvent.
  • Calculating moles: Use formula Mass = Moles x Molar mass, and rearrange to find the amount needed. Always verify calculations before proceeding.
  • Dissolving the Solute: Add the calculated amount of solute to a beaker and dissolve in distilled water.
  • Transfer to Volumetric Flask: Use a wash bottle and funnel to carefully transfer the solution, ensuring all solute is included. Top up to the mark with distilled water. Shake the flask gently to mix.

Section 3: Performing a Titration

  • Pipetting: Fill a pipette with the analyte and dispense it into a clean conical flask.
  • Adding Indicator: Add a few drops of an appropriate indicator to the conical flask.
  • Running the Titration: Fill the burette with the standard solution, noting the initial volume. Then gradually add the titrant to the flask, swirling to mix, until the end point (colour change) is achieved.
  • Measuring Volume: Record the final volume of titrant in the burette. The difference between initial and final volumes is the amount used in the reaction.

Section 4: Analysing Titration Results

  • Average Titre: Repeat the titration several times (replicates) to ensure accuracy. Calculate the average volume of titrant used (disregard any anomolous results).
  • Calculating Concentration of Analyte: Use formula Concentration = Moles ÷ Volume. Remember that the volume should be in dm3, so convert mL to dm3 by dividing by 1000.
  • Potential Errors: Possible errors include measurement inaccuracies, misjudging the end point, or not fully transferring solutions. Always use careful technique, and perform multiple replicates to minimise these errors.

Section 5: Safety and Disposal in Titration

  • Safety: Always wear protective equipment (glasses, coats, gloves) to guard against spills. Handle glassware, especially burettes, with care.
  • Disposal: After titration, dispose of solutions as per lab safety guidelines. Wash and rinse all glassware ready for next use.