List some advantages as well as disadvantages to using the Craig tube technique
ID: 1000989 • Letter: L
Question
List some advantages as well as disadvantages to using the Craig tube technique 1. What was the purpose of using activated charcoal in this experiment? Did you notice any differences before and after the addition of the activated charcoal? 2. 3. Describe the purpose of each of the following as they apply to recrystallization. a. Seed crystals b. Boiling stones c. Celite 4. Why must the acetanilide be completely dry before obtaining its melting point? d cooling generally give better crystals than rapid cooling? How do you know if you happen to use too much recrystallization solvent? If you encounter this problem, what can you do? 6. 7. Why do you think a stemless funnel was used rather than a long stem funnel during the gravity filration step? 8. How do the melting points of the impure acetanilide and the recrystallized acetanilide compare?Explanation / Answer
1) you cannot do small volumes without large loss due to sticking to sides of the beaker
2) need know the experimet because its posible than the carbon be used for trap the inpures present in the sustance
3)The large crystal can be grown by dipping the seed into a supersaturated solution, into molten material that is then cooled, or by growth on the seed face by passing vapor of the material to be grown over it.
Boiling chips work by providing nucleation than promoves the formation of crystals
celite promove the formation of crystals in oversaturade solution
4) because you need meter the melting poing of a compuest pure not of a mix of sustances include the sustance can be solved for the water and you meter the melt point of sustance in water and not the sustance pure
5) a low cooling give time for may formed a crystal because it the crystal is formed fast have little crystal than are more susceptible to atack of other sustances because have more superficial area
6) the solvent of recrystalization depend of the practic and solvent used but in general
if the solvent presipite the impureses too it is a problem you can heat to evaporate the solvent
7) because it possible than the crystal closed the exit
8) in general the impureses incresess the melting poing
1) yes because it are used for dont promove the formation of buble
2) becasuse the boiling point depend of the pressure it the pressure is over sea levels the pressure is a little more low and so you get a melting poing more low
3) the vacun have a 0 pressure and funtions so but if you heat incresess the pressure this pressure make the liquid be in less concentration in the gas phase make difficult the separation
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