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Questions and Answers
What is the purpose of the given laboratory procedures?
What is the purpose of the given laboratory procedures?
What piece of equipment is used to remove any undissolved solids from the solution?
What piece of equipment is used to remove any undissolved solids from the solution?
Which chemical is used to slowly add to the beaker containing the aluminum foil?
Which chemical is used to slowly add to the beaker containing the aluminum foil?
After gravity filtration, what should the solution in the Erlenmeyer flask look like?
After gravity filtration, what should the solution in the Erlenmeyer flask look like?
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What should be done to remove any potassium hydroxide after allowing the flask to cool?
What should be done to remove any potassium hydroxide after allowing the flask to cool?
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Which step of the procedure involves tearing aluminum foil into small pieces?
Which step of the procedure involves tearing aluminum foil into small pieces?
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What is the purpose of using a Büchner funnel during gravity filtration?
What is the purpose of using a Büchner funnel during gravity filtration?
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Which piece of equipment should be used to measure precisely 25 mL of 3M KOH?
Which piece of equipment should be used to measure precisely 25 mL of 3M KOH?
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Why is it important to fill the funnel only to within ½” of the top of the paper during filtration?
Why is it important to fill the funnel only to within ½” of the top of the paper during filtration?
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What role does parafilm play in the lab procedure?
What role does parafilm play in the lab procedure?
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Study Notes
Laboratory Experiment: Synthesis of Alum Crystals
- The experiment involves synthesizing alum crystals through a series of steps, including the reaction of aluminum foil with potassium hydroxide (KOH) and sulfuric acid (H2SO4).
Day 1 Procedures
- Clean all glassware before starting the experiment.
- Obtain 1 gram of aluminum foil, record its mass, and tear it into small pieces.
- In the fume hood, add 25 mL of 3M KOH to the beaker containing the aluminum, stirring slowly and carefully to produce a reaction.
- Filter the solution using a funnel and filter paper, removing any undissolved solids.
- Allow the flask to cool while washing the funnel and beaker with tap water to remove any potassium hydroxide.
Synthesis of Alum Crystals
- Add 35 mL of 3M H2SO4 to the flask, swirling the flask as the acid is added.
- The solution will get very hot, and a solid will precipitate and then dissolve as more H2SO4 is added.
- If there are any white flecks left in the solution, place the flask on the Bunsen burner apparatus and warm it with swirling until all of the solid material has dissolved.
- Allow the flask to cool, then place it in the ice bath and allow it to cool for an additional 5 minutes.
Crystallization
- If alum crystals have not started to form, scratch the inside walls of the flask with a stirring rod to provide sites for crystallization.
- Swirl the flask when crystal formation begins, and allow it to cool in the ice bath for another 10 minutes.
- Prepare a vacuum filtration apparatus, and wet the filter paper with distilled water.
Filtering and Drying
- Pour the solution into the Buchner funnel, and filter the alum crystals.
- Pour the filtrate into a beaker for disposal, and clean the filtering flask for storage.
- Label a clean dry watch glass with the period and group number, and place the filter paper and crystals on it.
- Set aside in a designated area for drying overnight.
Pre-Lab Questions
- A synthesis reaction is a type of reaction that involves the combination of two or more substances to form a new compound.
- A hydrated crystal is a crystal that contains water molecules within its structure.
- Step 2 must be completed in the fume hood because it produces fumes and heat.
- Washing the crystals with pure water is not recommended because it may cause the crystals to dissolve.
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Description
Learn about the steps involved in an organic chemistry lab procedure, including filtering and drying crystals. Understand the process of transferring mixtures, labeling equipment, and disposing of solutions under the guidance of an instructor.
