Question

Hey can I please get some help to complete this worksheet that is based on Synthesis and Recrystallization of Dibenzalacetone lab.

4. If you were to measure the melting point prior to recrystallization, what would you expect (compared to the melting point of the recrystallized product)? As. Comment of the purity of the product 6. Describe the color of the product. What is responsible for this color? iǐne (for 낙 product is aAbrrǐut yellow. A 7. Functional group questions: What functional group is found in acetone?: What two functional groups are in dibenzyl acetone? A 8. Dibenzalacetone is often used as an ingredient in sunscreen lotions and sprays. Suggest what properties are valuable in a compound for use as a sunscreen. You may need to consult reference sources. x9. Questions about recrystallization: (slowly/rapidly). To grow good crystals the solvent should cool Crystals form because the When done properly a pure crystalline form of the reaction product may be produced by recrystallization. of the solute decreases with decreasing temperature. There is no avoiding loss off some product using this method even with perfect technique but the loss is acceptable in order to obtain the crystalline form. Explain why it is unavoidable that some product will be lost during the recrystallization.

Answer 1

Answer 4: The melting point prior to the recrystallisation product will be lower than the melting point after recrystallisation of the product because presence impurities leads to lowering of the melting point of the substances. This is due to the fact that crystalline solid is made up of repeating units of molecules tightly held together. During the melting point determination, this lattice has to be disrupt at certain temperature. However, presence of impurities in the compound weakes the stability of lattice mad makes vulnerable to melt quite before the actual melting point.

Answer 7: The functional group present in the acetone is carbony group i.e. Ketone group

The two functional groups present in the dibenzalacetone are i) Ketone and ii) Olefin

Answer 8: The dibenzalacetone absorb,reflect, or scatter the UV rays which are harmful for skin and provides the protection from burning from UV rays. Because of this properties it is used in sunscreen creams.

Answer 9: To grow good crystals the solvent should cool slowly .

Crystals forms because the solubility of the solutes decreases with decreasing temperature.

Reasons: a) If you cool the solution slowy than the the crystal will form slowy. More slowy crystals will be higly pure in nature as compared to the crystals formed by fast cooling which can trap the impurities during fact crystallisation.