Question

How would the following actions effect both the yield AND the purity of your recrystallized trans-dibenzoyl ethylene

a) the dichloromethane solution is not treated with activated carbon

b) the crude crystals are not completely dissolved in the dichloromethane before filtering the activated carbon.

c) the 1 ml dichloromethane rinse is not applied to your flask and filter column

d) the crystals are not completely dissolved in hot ethanol before recrystallizing the trans-1,2- dibenzoylethylene

Answer 1

a) If it is not treated with activated carbon, it can't filter the organic colored impurities.But yield may not be affected.

b) Some of the crude crystals also adsorbed on charcoal, it effects the amount yield finally.

c) It affects the purification as any content(impurities) left in the flask is not cleaned properly. Hence it results finally in the purification of the yield.

d) Recrystallization is a purification technique. If the crystals are not dissolved in the solvent, it affects the purity of the substance.