Question

1. Give a well-reasoned explanation, with sufficient data, for your choice of method for each of the following separations. (If you can find a published method it can be used instead of a written response.) a. Separate chloride ions from bromide ions in samples of brine. b. Separate and quantify ascorbic acid from desoxyascorbic acid c. Separate, and quantify ortho, meta and para xylenes

Answer 1

1. Separation

a. Cl- and Br- ions : The two ions can be separated by adding aquoeus AgNO3 solution. Cl- forms a white precipitate of AgCl and Br- forms a yellow precipitate of AgBr. AgCl is more soluble when Br- is precipitated initially and only after increasing concentration of AgNO3, Cl- gets precipitated.

b. Separation of ascorbic acid and dehydroascorbic acid can be achieved on a HPLC column, the mixture composition can be found by this method and from it the overall percentages of ascorbic acid and dehydroscorbic acid in the sample can be calculated.

c. A very careful fractional distillation using a very long fractionating column allows us to separate the three isomers of xylenes.