Hi, I'm stuck on this chem practical question and was wondering if anyone could help. I've included my ideas so far in bold...
Salicylic acid can be used to make aspirin. Before using a sample of salicylic acid to make aspirin, a student purified the acid by recrystallisation. The method for recrystallisation is outline below:
Step 1 - The sample is dissolved in a minimum volume of hot water.
Step 2 - The solution is filtered hot.
Step 3 - The filtrate is cooled in ice to form crystals.
Step 4 - The crystals are collected by filtration, washed with cold water and left to dry.
Explain the purpose of each underlined point:
minimum volume and hot water -
Min volume of water as too much can mean crystals don't form, hot to dissolve the mixture.
filtered hot -
To stop the dissolved compounds recrystallising during filtration.
cooled in ice -
??
washed with cold water -
So the product/aspirin doesn't dissolve again and to wash away any soluble impurities.