Lab: Recrystallization Flashcards
1
Q
technique
A
dissolve a solid in hot solvent and then cool SLOWLY
2
Q
Why does recrystallization work?
A
the dissolved material has a DECREASED solubility at lower temperatures and will separate from the solution when cooled
3
Q
How is recrystallization different from precipitation?
A
- recrystallization is selective, precipitation is nonselective
- recrystallization the solution is cooled slowly, precipitation the solution is cooled rapidly
- recrystallization creates a pure material, precipitation creates an impure material
4
Q
How to choose a solvent? The product must be
A
- very soluble in hot solvent
- insoluble in cold solvent
5
Q
How to choose solvent? Impurities must be
A
completely soluble OR insoluble at all temperatures
6
Q
How to choose a solvent? Reactivity?
A
unreactive to compounds being dissolved
7
Q
How to choose a solvent? BP?
A
low
8
Q
How to choose solvent? Toxic?
A
nope
9
Q
BLANK the difference in temperature
A
maximize
10
Q
BLANK the contact with solvent
A
minimize
