weight loss cardiff answers:

The lab should be well ventilated, as chlorinated solvents are toxic and induce nausea and drowsiness.

Since CH2Cl2 is denser than water, the organic layer will be the lower layer. This can be drained off and more, fresh solvent can be added to the separatory funnel for a 2nd extraction.

If diethyl ether is used, the organic layer is the upper layer. The aqeuous layer has to be drained off, the organic layer decanted out of the top and, if a 2nd extraction is to be done, the aqueous layer has to then be returned to the separatory funnel. More transfers of layers means more losses of material.

weight loss cardiff answers:

First dissolve a few grams of the mixture in diethyl ether.

Next, extract the benzoic acid into an aqueous layer by adding saturated NaHCO3 to the ether solution in a separatory funnel. This should be done 3 times with small amounts of the saturated NaHCO3 solution. The benzoic acid will react with the NaHCO3 to form a salt that is soluble in the aqueous phase. The aqueous phase will be on the bottom because water is more dense than diethyl ether. Remember to vent the extraction flask often to reduce pressure due to CO2 gas being released in the chemical reaction. 2-naphthol will not dissolve in saturated NaHCO3.

Reaction: C6H5COOH(aq) + HCO3^-(aq) –> C6H5COO^-(aq) + CO2(g) + H2O

Recover the 2-naphthol by removing the ether. If you did a good job of extracting the solid should be fairly pure. You can check this by obtaining a melting point of the product after drying.

Recover the benzoic acid by adding concentrated HCl (caution) to the aqueous solution. The volume of acid you add depends on the amount of benzoic acid you have in the aqueous phase.

Reaction: C6H5COO^-(aq) + H3O^+(aq) –> C6H5COOH(s) + H2O(l)

The pH of the solution can be checked using pH paper as you add more concentrated HCl (add drop by drop) When the pH of the solution reaches about 1 then you can stop adding the acid and cool down the benzoic acid solution in an ice water bath. After the solution is cooled to about 0 degrees Celsius then you should use vacuum filtration to recover the product. Allow the product to dry in your equipment cabinet by leaving the filtered solid on a watch glass.

Hope this is helpful to you. JIL HIR

weight loss cardiff answers:

Acids are more easily dissolved in basic solution, bases are more easily dissolved in acidic solution.

Dissolving is an equilibrium reaction so partial solubility in one of the solutions will give an indication. If your unknown did not fully dissolve in acid or base this may be just an indication it is not a strong acid/base. Dissolving in diethyl ether is just an indication of the organic nature of your unknown. Details of solubility testing in this website [1]

Good luck 🙂