Orgo post lab questions 2 PDF

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Post-lab Questions:

3. Why should activated carbon be used during recrystallization? 

Activated charcoal is carbon treated with oxygen making it highly absorbent. Crystallization can help remove impurities but, the charcoal removes all of the impurities during the process so the crystals that form are completely pure.

5. Under which circumstances is it wise to use a mixture of solvents to carry out recrystallization? 

In the circumstance of a product with impurities gets dissolved in the first solvent, by adding a second solvent that only the impurity is soluble in, the product will them be separated from its impurity.

6. Why is gravity filtration rather than suction filtration used to remove suspended impurities and charcoal from a hot solution? 

Suction filtration is not used with a hot solution because it will cause it to boil then vaporize, so the suction will suck up the vapor instead of the actual liquid.

7. Why is fluted paper used in gravity filtration? 

Fluted paper is used because when a solvent is getting filtered, it will need to push air out as it goes in, so fluting the paper will allow it come out.

8. Why are stemless funnels used instead of long-stem funnels to filter hot solutions through fluted filter paper? 

This is because when solvent gets filtrated, the air must come out as the solvent is going in, but the funnel and flask have no gap to let the air out, so the long-stem funnel forces the air to stay in and slow down filtration, while the stemless funnel does the opposite.

9. Why is the final product from the recrystallization process isolated by vacuum filtration rather than gravity filtration? 

The crystals need to stay cold to remain pure and solid, the gravity filtration may warm up the solvent causing it to dissolve again, while the better option is the use the vacuum filtration because it will be able to remove the solvent while still cold....