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chem 6Al Q3 material Questions and
Correct Answers/ Latest Update / Already
Graded
Recrystallization
Ans: the process of dissolving solute in a hot solvent then
slowly cooling to form solid precipitate (purified product)
Why add hot solvent
Ans: allows us to use as little solvent as possible --> more
product
Why cool slowly
Ans: Prevents impurities from getting trapped in the reforming
crystalline lattice structure
Why use the minimum amount of hot solvent
Ans: too much = hard to recrystallize out when you cool = low
yield
We want a saturated solution for max yield
All rights reserved © 2025/ 2026 |
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Flask size
Ans: use as small of a beaker as possible
too large= hard to isolate the evenly distributed solid product
spread across the glass
Ideal solution
Ans: High solubility at high temperature
Low solubility at low temperatures
Can dissolve with heat and recrystallize by cooling
What to do if no crystals form
Ans: Nucleation site needed to give the product a starting
point to form the lattice structure and organize around
1) add a seed crystal = little bit of pure or crude product
2) scratch flask inside= microabrasions, might have the correct
structure
3) boil off excess solvent then re-cool
why wet the filter paper
All rights reserved © 2025/ 2026 |
chem 6Al Q3 material Questions and
Correct Answers/ Latest Update / Already
Graded
Recrystallization
Ans: the process of dissolving solute in a hot solvent then
slowly cooling to form solid precipitate (purified product)
Why add hot solvent
Ans: allows us to use as little solvent as possible --> more
product
Why cool slowly
Ans: Prevents impurities from getting trapped in the reforming
crystalline lattice structure
Why use the minimum amount of hot solvent
Ans: too much = hard to recrystallize out when you cool = low
yield
We want a saturated solution for max yield
All rights reserved © 2025/ 2026 |
, Page |2
Flask size
Ans: use as small of a beaker as possible
too large= hard to isolate the evenly distributed solid product
spread across the glass
Ideal solution
Ans: High solubility at high temperature
Low solubility at low temperatures
Can dissolve with heat and recrystallize by cooling
What to do if no crystals form
Ans: Nucleation site needed to give the product a starting
point to form the lattice structure and organize around
1) add a seed crystal = little bit of pure or crude product
2) scratch flask inside= microabrasions, might have the correct
structure
3) boil off excess solvent then re-cool
why wet the filter paper
All rights reserved © 2025/ 2026 |
