A student is instructed to standardize an approximately 2.5N KOH solution using a 0.500N H2SO4 stock solution. Describe the experimental procedure he/she must follow.
I do not understand what procedure needs to be followed.
Look in your text/notes for this procedure. I can type it up, probably, if I want to spend 30 minutes typing. ;-).
If you have some specific questions about the procedure I shall be happy to help.
Basically you want to do this.
1. Calculate the approximate amount of H2SO4 you want to titrate to use about at least 20 mL (more if possible) KOH.
2. Add the H2SO4 to a titration flask with a pipet.
3. Add indicator
4. Titrate with KOH to the end point.
To standardize a solution, the student needs to determine its exact concentration by comparing it with a known standard solution. In this case, they are instructed to standardize a 2.5N KOH solution using a 0.500N H2SO4 stock solution.
Here is the experimental procedure the student must follow:
1. Prepare the 0.500N H2SO4 stock solution: The student needs to accurately weigh the appropriate amount of H2SO4 (Sulfuric Acid) and dissolve it in a known volume of water, such as 1 liter, to obtain a 0.500N concentration. This preparation may require consulting reference materials or using specific lab procedures depending on the exact H2SO4 concentration and purity.
2. Set up the burette: A burette is a long, graduated tube used for precise volumetric measurements. The student needs to fill the burette with the 0.500N H2SO4 solution, ensuring there are no air bubbles and the lower meniscus is aligned with the calibration marks.
3. Obtain a sample of the approximately 2.5N KOH solution: The student should carefully measure a known volume of the 2.5N KOH solution using a volumetric pipette or a burette to transfer it to a flask.
4. Titration process: The student will perform a titration, which involves gradually adding the standard solution (0.500N H2SO4) to the KOH solution until the reaction between the two is complete. The reaction can be identified by observing a visual indicator or monitoring pH changes.
5. Indicator selection: The student must select an appropriate indicator (e.g., phenolphthalein) that will undergo a clear color change when the reaction is complete. This will indicate that all KOH has reacted with the H2SO4 in the flask.
6. Titration process continuation: The student will slowly add the H2SO4 solution from the burette to the flask containing the KOH solution, while carefully mixing or swirling the flask. The color change of the indicator will help to detect when the reaction is complete.
7. Endpoint determination: The student must continue adding the H2SO4 solution drop by drop until the indicator undergoes a noticeable color change indicating that all the KOH has reacted.
8. Record the volume used: The student needs to note the final volume of H2SO4 solution used to reach the endpoint. This volume will be used to calculate the concentration of the KOH solution.
9. Calculation: Finally, based on the stoichiometry of the reaction, the student can calculate the concentration of the KOH solution by comparing the volumes used and the known concentration of the standard H2SO4 solution.
It is vital for the student to follow proper lab safety procedures, handle chemicals carefully, and record all measurements accurately to obtain reliable and accurate results.