In The Lab: How to do a titration – properly.
TLDRIn this video, Professor L demonstrates the process of performing a titration, an essential technique in chemistry used to determine the concentration of an unknown solution. The demonstration focuses on an acid-base titration using hydrochloric acid and sodium hydroxide. Key steps include filling the buret, removing air bubbles, and accurately adding the titrant while swirling the solution. The video highlights the importance of precision and reproducibility in titrations, offering tips for achieving accurate results. The goal is to reach the end point where the solution changes color, allowing for the calculation of the unknown concentration.
Takeaways
- 🔬 Titrations are essential in chemistry for determining the concentrations of unknown solutions by using known solutions.
- 📏 The key equipment for titration includes a buret, which is precise for delivering specific volumes of solution.
- ⚗️ For a classic acid-base titration, hydrochloric acid (HCl) is titrated against sodium hydroxide (NaOH).
- 🔍 Proper technique involves filling the buret carefully using a funnel to avoid spills and ensuring there are no air bubbles in the buret tip.
- 🌡️ It's crucial to overfill the buret slightly and then adjust to the zero mark for accurate measurement.
- 💧 The addition of a few drops of phenolphthalein indicator helps in visualizing the endpoint of the titration.
- 🌈 The endpoint of the titration is indicated by a persistent pale pink color in the solution.
- 📐 Accurate reading of the buret volume is necessary, typically to two decimal places for precision.
- 🔄 Reproducibility is key; conducting multiple titrations and obtaining concordant results ensures accuracy.
- 🧮 After achieving concordant results, stoichiometry calculations can be performed to determine the concentration of the unknown solution.
Q & A
What is the fundamental basis of a titration?
-The fundamental basis of a titration is to determine the concentration of an unknown solution by using a known solution to react with it, involving a bit of stoichiometry to perform the necessary calculations.
What equipment is essential for performing a titration?
-The essential equipment for performing a titration includes a buret for accurately delivering specific volumes, and the solutions to be titrated. In this case, an Erlenmeyer flask containing hydrochloric acid and a buret filled with sodium hydroxide.
Why should you avoid filling a buret by hand without a funnel?
-You should avoid filling a buret by hand without a funnel because it can lead to the solution running down the outside of the buret, causing inaccuracies and potential spills. A funnel ensures a steady and controlled fill.
Why is it important to remove the funnel after filling the buret?
-It is important to remove the funnel after filling the buret to prevent drops of the titrant in the funnel from coming down and affecting your reading.
What common mistake should be avoided regarding air bubbles in the buret?
-A common mistake to avoid is having air bubbles in the buret tip. Air bubbles can cause inaccuracies in the titration. To remove air bubbles, lay the buret flat, open the tap slowly, and let the air bubble disappear.
What should you do if your buret tip has sodium hydroxide on it before starting the titration?
-If your buret tip has sodium hydroxide on it before starting the titration, you should wipe it off to ensure it does not affect your titration results.
How can you ensure that you don't miss the target while swirling the Erlenmeyer flask during titration?
-To ensure you don't miss the target while swirling the Erlenmeyer flask, keep the level of the buret tip below the level of the top of the flask. This prevents any drops from falling outside the flask during swirling.
How many drops of phenolphthalein indicator are needed for the titration?
-Only a couple of drops of phenolphthalein indicator are needed for the titration. More indicator is not necessary and can affect the results.
What is the correct technique for adding the titrant during a titration?
-The correct technique for adding the titrant during a titration is to swirl the Erlenmeyer flask with one hand and operate the buret tap with the other, adding the titrant dropwise as you approach the end point where the solution changes color.
How do you know when you have reached the end point of the titration?
-You know you have reached the end point of the titration when the solution in the Erlenmeyer flask changes to a very pale pink color that persists. Adding additional drops of titrant will make the solution more pink, confirming the end point.
Outlines
🔬 Introduction to Titration
The host introduces titration, emphasizing its importance in chemistry for determining unknown solution concentrations using known solutions. The setup for a classic acid-base titration between hydrochloric acid and sodium hydroxide is described, including the necessary equipment such as a buret and Erlenmeyer flask. The procedure begins with filling the buret with sodium hydroxide solution, highlighting the importance of using a funnel to avoid spills and removing it after filling to prevent contamination.
💧 Preparing for Titration
The host continues with the titration setup, explaining how to fill the buret to the zero line and eliminate air bubbles, which is crucial for accurate measurements. Tips are provided for avoiding common mistakes, such as leaving the funnel in the buret or not removing air bubbles properly. The importance of ensuring no sodium hydroxide remains on the buret tip is also stressed to prevent affecting titration results.
🔍 Performing the Titration
The host demonstrates the titration process, explaining how to position the Erlenmeyer flask under the buret and the technique for adding the sodium hydroxide solution while swirling the flask. The use of phenolphthalein as an indicator is discussed, with advice on the amount to use. The titration is performed by gradually adding the titrant and observing the color change to identify the endpoint. The host emphasizes the need for precise control and visualization of the pale pink color indicating the titration endpoint.
Mindmap
Keywords
💡Titration
💡Buret
💡Stoichiometry
💡Indicator
💡End Point
💡Erlenmeyer Flask
💡Meniscus
💡Concordant Titrations
💡Phenolphthalein
💡Experimental Uncertainty
Highlights
Titrations are crucial in chemistry for determining unknown concentrations using known solutions.
A buret is a precise instrument for delivering specific volumes in titrations.
It is essential to use a funnel to fill the buret to avoid spilling the solution.
Always remove the funnel after filling the buret to prevent additional drops from affecting the reading.
Ensure there are no air bubbles in the buret tip, as they can affect the titration results.
To remove air bubbles, lay the buret flat and open the tap slowly until the bubble disappears.
Refill the buret to the zero line after removing air bubbles to ensure accuracy.
Phenolphthalein is used as an indicator in acid-base titrations; only a couple of drops are needed.
Operate the buret with one hand and swirl the Erlenmeyer flask with the other for precise control.
Start adding the titrant quickly at first and then slow down as you approach the end point.
The end point is indicated by a persistent pale pink color in the solution.
Add titrant dropwise as you near the end point to avoid overshooting the target.
To confirm the end point, note the reading and add another drop to check if the color changes more.
Record the titration volume to two decimal places for precise results.
Titrations need to be reproducible; perform multiple titrations to ensure consistent results.
Concordant titrations are when two titrations agree within experimental uncertainty, typically ±0.05 mL.
Accurate stoichiometry calculations are based on precise titration results.
Transcripts
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