2 titri

Introduction to Titration

• Titration is a technique used to quantitatively determine the concentration of an unknown solution (titrand or analyte).

• A solution with a known concentration is added (titrant) until the endpoint is reached, often indicated by a color change.

Equipment Required for Titration

Complete Burette Assembly Kit

• Available from Carolina Biological Supply Company.

• Consists of:

  • Burette: A long narrow graduated tube, used for adding titrant, equipped with a stopcock to control flow.

  • Ring Stand and Burette Clamp: Used to securely hold the burette in a vertical position.

Additional Materials Needed

• Funnel: Assists in filling the burette.

• Erlenmeyer Flask (125 mL): Preferred for titrations due to its shape allowing for vigorous swirling and minimizing spill hazards.

• Volumetric Pipette and Bulb: To transfer a precise volume of analyte to the flask.

• Wash Bottle with Deionized Water: For rinsing equipment.

• Beaker or Flask of Titrant and Analyte: Containers for the solutions used in the titration.

• Indicators: Chosen based on the specific chemical reaction.

• Reading Card: Helps in accurate meniscus reading.

• White Sheet of Paper: Aids in visualizing the endpoint during titration.

Preparing the Burette

• Rinsing the Burette:

  • Rinse thoroughly first with deionized water, then with a small amount of titrant.

  • After rinsing, open the stopcock to drain excess liquid; ensure no residue clings to walls (may require thorough cleaning).

• Mounting the Burette:

  • Ensure it is vertical with enough space for the flask below.

• Filling the Burette:

  • Fill with titrant to just below the top mark—too full can cause overflow.

  • Remove any air bubbles by gently tapping the bureau walls before removing the funnel.

Start of the Titration

• Initial Setup:

  • Place the Erlenmeyer flask under the burette and allow a few mL of titrant to flow through to release trapped air.

  • Rinse the tip of the burette with water to eliminate any residual titrant and waste it appropriately.

• Recording Volume:

  • Read and record the starting volume from the bottom of the meniscus at eye level, taking care to use correct significant figures (to the hundredth mL for this burette).

Performing the Titration

1. Adding Analyte:

   • Transfer known volume of analyte using volumetric pipette into the flask.

   • Add indicator drops and swirl to mix.

2. **Operating Burette: **

   • Requires two hands: one for the stopcock and one for swirling the flask.

   • Start with an estimate for the first titration; open the stopcock quickly, so titrant flows while swirling.

3. Determining the Endpoint:

   • As titrant is added, observe the color change of the analyte.

   • Close the stopcock when the solution reaches a color change, which indicates nearing the endpoint.

   • Record the final volume and calculate the volume of titrant used.

Refining the Process

• Final Titration Adjustments:

  • If the analyte shows a dark color, excess titrant has been added. Aim for a pale hint of color as the endpoint.

  • Slow down the titrant addition when color appears, adjusting to dropwise additions.

• Determining Endpoint Precise:

  • Repeat the drop addition and swirling until a faint color persists, indicating the endpoint.

Replicating Titrations

• It is common laboratory practice to conduct titrations in triplicate to ensure accuracy.

• Use the average volume of titrant required to determine concentration calculations.

Conclusion

• Mastery of titration techniques facilitates accurate chemical analysis.

• For additional techniques, check the second video in this series focusing on the determination of unknown acid concentrations.

• Carolina offers a variety of products for chemistry labs. Visit CarolinaChemistry.com for more details on available kits and equipment.