Question

Organic Chemistry Lab question

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 NaOH solution to the separatory funnel and placed the stopper over the top of the separatory funnel. Shook the funnel to mix the two layers and drained the aqueous layer into a test tube #1. We did this again (2 mL of 1.0M NaOH) and repeated the extraction and placed the contents into test tube #2. To check for impurity, we added 6.0 M HCl to both test tubes. No precipitate formed so WE KNOW THERE IS NOT AN ACIDIC IMPURITY.

Now we did the same thing twice with test tube #3 and #4, but instead pouring approximately 2 mL of 1.0 HCl solution to the separatory funnel and gently shook the contents for 30 seconds to mix the two layers. Drained the aqueous later twice into test tube #3 and #4. Both formed precipitates but Test tube #4 had the most. WHY IS THIS?

We then added 6.0 M of NaOH to test tubes #3 and 4 and found a precipitate formed. Because of this we know we had a basic impurity so the impurity must be 4-chloroaniline. Upon getting a melting point, I identified my unknown as Fluorenone. (Melting point was around 82-84 degrees celsius)

The questions I NEED HELP WITH:

"Discuss why a precipitate is observed by describing the structure of the impurity (in this case 4-chloroaniline) and the reactions involved. Describe what impurity was in your impure unknown and how you determined this"

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! :) Please be as thorough as possible