Please help me with these questions! 1. Suppose you want to purify compound A by
ID: 810032 • Letter: P
Question
Please help me with these questions!
1. Suppose you want to purify compound A by re-crystallization. Below you see the solubility of A in different solvents. Which solvent would be the best for recrystallization of A? Explain briefly why. 2. What is the reason for using charcoal during re-crystallization? Describe briefly what is the role of charcoal, when and how it is used. 3. Suppose you have three test tubes with three substances, A, B, and C with nearly the same melting point. Describe how would you proof experimentally (having only melting point apparatus in hand) that these are not the same substances.Explanation / Answer
Q1.)the best sovent would be ethanol because A is very soluble in ethanol at boinling point and comparitively less soluble at room temperature and that is the method to select a good solvent if we have only the data about solubitlity in different solvents.
Q2.)Charcoal is used in re-crystallisation because sometimes there are impurities which bring color to our required product which is generally colorless.But we have to use only a small amount of charcoal otherwise the product will also get adsorbed with the impurity.
Q3.)we can use the following procedure to differentiate them:
Take a mixture of A and B(a small amount will suffice).Mix them properly.Now measure the melting point of the mixture.If they are the same compound the melting point of the mixture will be the same as that of the individual components otherwise one will act as an impurity and the melting point of the mixture will be lower than that of the individual components. The same procedure can be follwed to show that A,B and C are different compounds.