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Scientific practical techniques question?
From the following method can anyone help me in identifying any possible sources of error that would influence both the yield and purity of the product?

Method

(a) Condensation
1. Place 1.5 cm3 of your chosen carbonyl in a test-tube and add 15 cm3 of 2,4 – DNPH to each tube.
2. Warm for a few minutes in a water bath and the cool to allow the crystals to form.
3. Filter off your crystals under reduced pressure using the Buchner Funnel and pump; see the diagram below. Wash with a little water then dry on a filter paper.
(b) Recrystalisation
1. Remove the crystals from the funnel on the filter paper and place in a small beaker.
2. Using a hot plate warm up some ethanol.
3. Carefully add a minimum volume of the warmed ethanol to dissolve the crystals and set aside to cool. NB: If too much solvent is used then the crystals will dissolve and not reappear.
4. Clean the Buchner apparatus and set up ready for use again.
5. Once the solution is cool and the 2,4-DNPH crystals have formed then filter using the Buchner apparatus again.
6. Wash the purified acid crystals with a little cold ethanol and then remove from the funnel as before.
7. Dry the 2,4-DNPH crystals, weigh them

Thank you!
asked in Organic chemistry



cryptminder answers:

The only thing that could affect the putity, is if anything comes into contact with either an element or piece of equipment that could contaminate your result. Everything must be absolutly clean


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