How to do a titration and calculate the concentration
TLDRThis instructional video demonstrates the process of a titration experiment to determine the concentration of an unknown substance. It outlines the necessary equipment, including a burette, beakers, a conical flask, and phenolphthalein as an indicator. The tutorial covers the initial setup, including rinsing apparatus and filling the burette with the titrant, NaOH. It then guides through the titration steps, emphasizing the importance of careful observation for the endpoint. Finally, it explains how to calculate the concentration of the unknown acid, HCl, using the balanced chemical equation and the average volume change from multiple titrations.
Takeaways
- 🔬 A titration is an experiment used to determine the concentration of an unknown substance.
- 🧪 The main apparatus needed for a titration includes a pipette, beakers, a burette, a conical flask, a white tile, and phenolphthalein as an indicator.
- 💧 Deionized water is used to rinse the apparatus to avoid any reactions.
- 📝 It's crucial to ensure the burette is closed to prevent the flow of the known substance, NaOH in this case.
- 📐 The pipette is used to measure 25 mL of the unknown substance, HCl, accurately.
- 📉 The initial reading of the burette is taken before starting the titration to three decimal places using a white tile for contrast.
- 🌈 Phenolphthalein indicator is added to the unknown solution to observe the color change during titration.
- 🤲 When titrating, the burette is held with one hand while the other hand controls the conical flask to add the known substance drop by drop.
- 🔴 The endpoint of the titration is reached when the pink color of the phenolphthalein stays, indicating the reaction is complete.
- 📊 After performing multiple titrations, an average change in volume can be calculated to determine the concentration of the unknown solution.
- ⚖️ A balanced chemical equation is created to understand the reaction between the acid (HCl) and the base (NaOH), forming a salt (NaCl) and water (H2O).
- 📚 The concentration of the unknown acid is calculated using the formula and the average volume change from the titrations, resulting in a concentration of 0.05 moles per decimeter cubed.
Q & A
What is the purpose of a titration?
-A titration is used to calculate the concentration of an unknown substance by reacting it with a known substance of known concentration.
What apparatus is needed for a titration experiment?
-The necessary apparatus includes a burette, a beaker for the titrant (NaOH in this case), a beaker for the titrand (HCl in this case), a conical flask, a white tile, a dropper, phenolphthalein as an indicator, and a retort stand.
Why is it important to rinse the apparatus before starting the titration?
-Rinsing the apparatus with deionized water is crucial to avoid any contamination that could affect the accuracy of the titration results.
Why should the burette not be cleaned before filling it with the titrant?
-The burette should not be cleaned because cleaning it could introduce water into the titrant, which would dilute the solution and affect the titration results.
How is the burette filled with the titrant?
-The burette is filled by ensuring it is closed, then filling it with the titrant (NaOH in this case), and making sure it is at a reading, not necessarily at zero.
What is the purpose of using a white tile during the titration?
-The white tile is used to provide a clear background against which the color change of the solution can be observed, which is essential for determining the endpoint of the titration.
How many drops of phenolphthalein are added to the titrand?
-Three drops of phenolphthalein are added to the titrand (HCl in this case).
What is the initial reading taken from the burette before starting the titration?
-The initial reading is taken from the burette by placing a white tile behind it and measuring from the bottom of the concave meniscus to three decimal places.
How is the titration performed?
-The titration is performed by holding the burette tap with one hand, spinning the conical flask with the other hand, and slowly adding the titrant drop by drop until the endpoint is reached, indicated by a persistent pink color.
How is the concentration of the unknown solution calculated after the titration?
-The concentration of the unknown solution is calculated by using the balanced chemical equation, the volume of the titrant used, and the concentration of the titrant. The formula involves the moles of acid reacting with moles of base to form a salt and water.
What was the average volume change obtained after three titrations in the script?
-The average volume change obtained after three titrations was 13.66 mL.
How is the concentration of the acid determined from the titration results?
-The concentration of the acid (HCl) is determined by dividing the product of the volume of the acid and the concentration of the base (NaOH) by the volume of the acid used in the titration.
Outlines
🧪 Setting Up for a Chemistry Titration Experiment
This paragraph introduces the process of a titration experiment, which is used to determine the concentration of an unknown substance. The narrator lists the necessary apparatus including a 25 ml burette, beakers, a conical flask, a white tile, a burette stand, and phenolphthalein as an indicator. The importance of rinsing all apparatus with deionized water is emphasized to avoid reactions. The burette is filled with the known substance, NaOH, and care is taken to ensure it's closed to prevent leakage. A 25 ml volume of the unknown substance, HCl, is measured using a burette and transferred to the conical flask. The narrator also explains the procedure for adding the indicator and taking initial readings with the burette, setting the stage for the titration process.
📊 Conducting the Titration and Calculating Concentration
In this paragraph, the actual titration process is described, where the known substance (NaOH) is added dropwise to the unknown substance (HCl) in the conical flask until the endpoint is reached, indicated by the persistent pink color due to phenolphthalein. The narrator explains how to handle the burette and conical flask to ensure accurate titration. After completing the titration, the final volume reading of the burette is taken to calculate the change in volume. The average change in volume from three titrations is determined to be 13.66 ml. Using a balanced chemical equation (HCl + NaOH → NaCl + H2O), the narrator demonstrates how to calculate the concentration of the unknown acid (HCl) by substituting the known values into the formula. The calculation concludes with the concentration of the acid being approximately 0.05 moles per decimeter cubed, rounded to two decimal places.
Mindmap
Keywords
💡Titration
💡Apparatus
💡Concentration
💡Indicator
💡Endpoint
💡Burette
💡Titrand
💡Titrant
💡Balanced Equation
💡Moles
💡Decim Cubed
Highlights
Introduction to the process of titration for calculating the concentration of an unknown substance.
List of necessary apparatus for the titration experiment including a petri dish, beakers, a burette, a conical flask, and a white tile.
The importance of rinsing all apparatus with deionized water to avoid reactions.
Filling the burette with the known substance, NaOH, and ensuring it's closed to prevent leakage.
Using a 25 mL pipette to accurately measure the unknown substance, HCl, into the conical flask.
Adding phenolphthalein as an indicator to the titrand to observe color changes during the titration.
The method to record the initial volume reading from the burette using a white tile for clarity.
Technique for slowly adding the titrant to the titrand while observing for the持久 pink color change.
Final volume reading from the burette to determine the change in volume during titration.
Performing multiple titrations to obtain an average change in volume for more accurate calculations.
Creating a balanced chemical equation for the reaction between HCl and NaOH to form NaCl and H2O.
Using the balanced equation and the stoichiometry to calculate the concentration of the unknown acid.
Explanation of how to manipulate the formula to solve for the unknown concentration of the acid.
Final calculation revealing the concentration of the unknown acid as 0.05 moles per decimeter cubed.
Clarification on the use of decimeters cubed versus centimeters cubed and the irrelevance due to the ratio used in calculations.
Summary of the titration process, emphasizing the importance of accuracy and observation for successful results.
Transcripts
5.0 / 5 (0 votes)
Thanks for rating: