purification by recrystallisation: steps + explainations
No description yet. This curated deck is ready for daily study.
Card preview (7)
give the 6 steps to purification by recrystallisation
• dissolve crude product in hot solvent/water • of minimum volume • filter • cool to recrystalise • filter under reduced pressure/ with Buchner apparatus • wash (with ice cold solvent) and dry
why do you do this? • dissolve crude product in hot solvent/water
to dissolve as much as possible
why do you do this? • of minimum volume
to make sure hot solution is saturated/crystals form on cooling
why do you do this? filter
to remove any soluble impurities
why do you do this? cool to recrystalise
yield is lower if warm/solubility higher if warm
why do you do this? filter under reduced pressure/with Buchner appartus
crystal compressed in Buchner funnel to allow for better drying as air passes through the sample
why do you do this? wash with ice cold solvent and dry
to wash away soluble impurities