1.)How does the use of fluted filter paper hasten filtration? Why is it advisable to place a small piece of wire between the funnel and the mouth of the flask during hot filtration?
The way the fluted filter paper is folded hastens filtration because it increases the surface area of the filter paper, giving the solution more area to go through.
A piece of wire is placed to avoid build-up of pressure, and easily pour the solution without spilling.
2.)Enumerate 2 techniques that can help prevent premature recrystallization. Explain each item. What can be the consequence if premature recrystallization was not avoided to occur?
Premature recrystallization happens when the solution cools down while it is being poured. To avoid this, the funnel may be kept warm using steam, and immediately drying with a towel or flame. To make sure that the solution will not have time to cool, hot solution may be tipped into the filter. This will keep the solution warm and will therefore keep it from crystallizing.
Since some of the sample would have been crystallized, a lower yield would be observed.
3.)A mixture containing 2.0g of A and 8.0g of B is to be separated and the components purified by one crystallization from 100 mL of solvent.
4.)A mixture of three compounds, A, B, and C, is to be separated and purified by crystallization. Their solubilities in g/100 mL ethanol are given below.
5.)You need to perform a recrystallization using a mixed-solvent system. Which of the ff. solvents could not be used as a solvent airs for the experiment? Explain your selection.
Hexane and water. A mixed solvent must contain two miscible solvents, in which hexane and water are not.
6.)What are the advantages/disadvantages of mixed solvent recrystallization over single solvent recrystallization?
Heating is not required when using mixed solvent crystallization, but it can be used. It also gives a more accurate result than when using single solvent recrystallization. A disadvantage is that one needs to go through more trials to find the right solvent pair. There is also a chance that the first solvent would be added in excess and in which case, one would need a large amount of the second solvent.