This isa methods for purifiying a solid which is in crystalline form.
Method:
1.Dissolve in a hot solvent (minimum amount) to remove soluble impurities.
2.Filter out all of the insoluble impurities from the hot solution
3. leave to cool
4. filter the cold solution
5. Wash and dry your product.
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Refluxing
This is where you continuously heat a reaction allowing the reacts to boil and condense to allow the reaction to go to completion. You will have used this technique in the formation of Aldehydes /ketones/carboxylic acids.This technique also helps to prevent the release of toxic fumes and allows the reaction to continue for longer
You will need
Pear shaped flask
Water condenser
A heating mantle
refluxing columm
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Melting point determination
You will need
Busen
Tripod
Gauze
Heat proof mat
Match
Thermometer
and 1cm of a sample to be tested in a capillary tube
you must record the temp at which the sample begins to melt and the temperatur at which all of the sample has melted, these two valu should be fairly close no more than 5 degrees apart for a practical assessment ( this is a popular topic for one for Edexcel). For substances which have a temperature which is greater than 100 degrees water cannot be used so it is changed for sand or oil.The purity of the substance can be guessed byhow close the values are because impuiies will increase the melting point and widen the range of values achieved.
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Boiling point determination
You will need
Busen
Gauze
Beaker
Heat proof mat
Thermometer
1cm Sample in a test tube anda cappillary tube inside the sample test tube
Match
Stirrer- so you have constant temp in the beaker
Tripod
Record the tep wen bubbles first start o appear form the capppillary tube and the temp at which they begin to form rapidly ( a rolling boil it is sometimes called in cook books).Then leave it to cool recording the temperature that the bubbles stop. All of these temperatures should be pretty close together.Problems can occur with accuracy because you measure the temp of the water and assume that the temp is the same in the sample tube.The points are hard to judge as well. Instead you could use fractional distillation instead.
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steam distillation
This technique is used to remove essentail oils from oranges and lemons. You have to pass steam through the mixture and add water after this you boil the mixture and distill off the product that you want.
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