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What are the three properties that a compound must possess in order for it to function well as an extraction solvent?
- the solvent must be miscible with the organic solute and not miscible with water- also any chemical reaction is permitted- higher yield of extraction- easy and complete recovery of the solvent
What are the adavantages of using ether as an extraction solvent?
The major disadvantage of using ether as an extracting solvent is that it is very flammable. It also oxidizes into an explosive in some cases, is an anesthetic, and is very vapor dense (meaning it will fall to the floor and move around there).
What hazards should you be aware of when evaporating a solvent from a solution?
one may inhale the harmful particles of that solution
What is the difference between a solute and a solvent?
In a solution, the substance present in the largest amount is considered the solvent, and the other(s) is/are considered the solute(s). Example: 1 ml ethanol + 2 ml H2O: water is the solvent and ethanol is the solute. 1 ml H2O + 2 ml ethanol: ethanol is the solvent and H2O is the solute.
What are the desirable properties of a recrystallization solvent?
One property that a solvent should have to be well suited for recrystallization of a particular compound is high solubility. It should also readily dissolve the organic compound at high temperature and precipitate the compound at low temperature.
Why repeated extraction is better than solvent extraction?
Because you are providing a greater surface area of contact between the aqueous layer and organic layer
Is it better to do a series of small volume extractions or one large one in solvent extractions?
It's normally better to do a series of small ones, 2 or 3 should be plenty. The reason is that if each time you get for example 95% extraction, you stand a better chance of retaining more product from a multiple extraction.
What are the three properties that a compound must possess in order for it to function well as an extraction solvent?
- the solvent must be miscible with the organic solute and not miscible with water- also any chemical reaction is permitted- higher yield of extraction- easy and complete recovery of the solvent
Why should the jar used to develop TLC plates be covered?
The jar should be covered so that it is saturated with the vapours of the volatile solvent before the plate is allowed to run.
What volume of an organic solvent should be used to effect a 90 percent separation in one extraction when only 2.7gm of a certain organic compound dissolves in 100 ml of water?
Pigment.
Why should the recrystallization solvent have a fairly low boiling point?
the more solvent you use the more of the poorly soluable compound (wich you are trying to crystallise) will be lost when you cool down your solvent. because the soluability at the lower temperature is still not 0 g/l.
Solvent for recrystallization?
A good solvent for recrystallization depends entirely on the polarity of the solid you're trying to purify. For example sodium chloride readily dissolves in water whereas naphthalene dissolves only in nonpolar solvents like hexane. To select a good solvent first consider the polarity of the compound of interest and pick a solvent that has the potential to dissolve it. Next suspend the solid in that solvent. You must pick another solvent if the solid completely dissolves in the selected solvent. Heat the mixture while stirring. If you reach the boiling point of the solvent and the compound hasn't dissolved, you must find a different solvent or add more of the solvent you are currently using. If your solid completely dissolves without too much of the chosen solvent, you have yourself a good solvent for recrystallization. To continue with the recrystallization simply allow the solvent to cool and your solid should precipitate out in the form of crystals. Put it in an ice bath to assist with the precipitation. The latter technique can lead to small crystals or powder. The best way to remedy this is to do a slow recrystallization. To do this you must use two solvents that will evaporate over a long period of time. One solvent must be very volatile and must be able to easily dissolve your compound at room temp. The other must be less volatile and your compound must be insoluble in this solvent. Note that this solvent must have the potential for dissolving the impurities in your compound. To perform the recrystallization, dissolve your compound in the "good" solvent and then add about the same amount of the "bad" solvent. Over a period of time, the "good" solvent should evaporate leaving your crystallized product in the "bad" solvent without any impurities.
What should be your prime concern when dealing with volatile liquids and gas leakage?
what should be our prime concern when dealing with volatile liquids and gas leakage
What are the properties of a perfect fixative?
it should be stable and should be volatile in nature.
What are the adavantages of using ether as an extraction solvent?
The major disadvantage of using ether as an extracting solvent is that it is very flammable. It also oxidizes into an explosive in some cases, is an anesthetic, and is very vapor dense (meaning it will fall to the floor and move around there).
What are the criteria in choosing a good recrystallization solvent?
Dissolve the entire compound at the boiling point of the solvent.Dissolve very little or none of the compound when the solvent is at room temperature.Have different solubilities for the compound and the impuritiesHave a boiling point below the melting point of the compound so that the compound actually dissolves, not melts, in the hot solvent.Have a relatively low boiling point.
How do you clean lamp oil out of a couch?
get out as much as you can using a WHITE towel, the only thing that will break it down is not a soap, it would be a solvent. A volatile dry solvent (perchloretheline) commonly used at dry cleaning shops. Pick up a phone book, look under cleaning-suppliers. find a place that sells carpet cleaning chemicals, (if you live in a metropolitan area, this should be easy) ask for a VDS or clean, dry solvent (not citrus based).
