(PLEASE only answer if will answer all parts of my question will rate good (: )
In the experiment we did acid-base extractions to find impurities. The impurity was either benzoic acid (acid) or 4-chloroaniline (base)
So, in this experiment we did Acid-Base extraction with an unknown compound. So, we had an unknown of 0.150 grams and mixed it with 20 mL of diethyl ether. We placed this in a separatory funnel and added 2mL of 1.0 HCl solution to the separatory funnel and placed the stopper over the top of the separatory funnel. Gently shook the funnel to mix the two layers and drained the aqueous layer into a test tube #3. We did this again (2 mL of 1.0M HCl) and repeated the extraction and placed the contents into test tube #4. To check for impurity, we added 6.0 M NaOH to both test tubes until basic. Precipitate formed. Both formed precipitates but Test tube #4 had the most. WHY IS THIS?
Upon getting a melting point, I identified my unknown as Fluorenone. (Melting point was around 111-114 degrees Celsius)
The questions I NEED HELP WITH:
- Describe what impurity was in your impure unknown and how you determined this?
-Why is a precipitate observed by describing the structure of the impurity and the reactions involved/ possible experimental error?
I was also confused because it asked me "which test tube had the most precipitate and why?" My test tube #4 had the most but I'm not sure why it had more than test tube #3?
Please I need any help I can get!
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Procedure II: Removal of impurity with HCI Place a 50-mL separatory funnel inside a ring clamp which is connected to a ring stand. Add approximately 2 mL of 1.0 M HCl solution to the separatory funnel and place the stopper over the top of the separatory funnel. Gently shake the contents in the separatory funnel for about 30 seconds to mix the two layers. Make sure the internal pressure in the separatory funnel is released at least once by opening the stopcock in a hood as the separatory funnel is held upside down with your thumb over the stopper. Return the separatory funnel to the ring clamp and after allowing about 1-2 minutes for the layers to separate, remove the stopper from the separatory funnel and drain the aqueous layer into test tube # 3. Which layer is the aqueous layer? What happens when you attempt to drain the contents in the separatory funnel without removing the stopper (try it once)? If an emulsion forms, allow an additional 5-10 minutes for the layers to separate. It may be necessary to break up the emulsion by gently stirring the contents of the separatory funnel with a stirring rod. Adding a small amount of saturated sodium chloride solution (brine) may also help to break up the emulsion.
Add an additional 2 mL of 1.0 M HCl to the separatory funnel and repeat the extraction procedure above. Once again remove the aqueous layer and place it into test tube # 4. Add dropwise 6.0 M NaOH solution to both test tubes # 3 and # 4 until the contents in each test tube are basic. The pH can be tested by dipping a spatula in the test tubes and then touching a strip of litmus paper with the wet spatula. Observe if any precipitate forms in either or both test tubes and record your observations in your notebook in a similar table to Table 3. If precipitate does form, make an observation of which test tube has more precipitate and move directly to the drying procedure. What do you think the precipitate is? What type of impurity do you think was removed using this procedure? If no precipitate forms in either test tube, then perform procedure I unless you have already performed it.