[UAphenix]

I am doing a lab write up for O-chem lab and have to answer a few questions and integrate them into my discussion.  If I coulf get any help at all it would be great.  The lab was on recrystalization and determine % recovery and melting points. here are the questions:
1.Why is important to use a minimal amount of hot solvent during a recrystallization?    What would happen if you used too much solvent while dissolving your solids?

2.Why is it important to cool the disolved product/solvent mixtures slowly during a recrystallization?

3.What is a possible explanation for not getting a large % recovery, think in terms of solvent, solubility, temp...etc

I have no clue on question 1, on question 2 I think it's because if you cool the mixtured too fast than the crystals won't have time to form.  On question 3 I understand the reason for getting a small % recovery when it comes to impurities, but I don't know how solvent, solubility or temp really figure into it all.  I have looked for answers to these on google and could really fund anything that would help. Thanks again for the help  

[mike]

1. Minimal solvent makes it easier to get more product back out of solution. Use too much and the product you want to recover will stay in solution.

2. Imagine if you cooled it super fast, pretty much anything dissolved in the solution will "crash" out of solution and form a solid (ie the product you want as well as all the impurities) you are trying to keep the impurities in solution while carefully crystalising your product.

3. Similar to the previous two questions: solvent (too much, too soluble, not soluble enough how would this affect the result?) solubility (if your product is highly soluble do you think it will be easy to get it out of solution? If it is barely soluble you would filter off all your product in the filtration stage) temperature (in general solubility is greater in hot solvent than in cold solvent, this is vital for recrystallisation, however if the solution is too cold to start with then not enough product will dissolve, and conversely if it is too hot then a lot of your product will still be in solution when you are trying to recover it)

Hope this helps

Mike