What is going on in the hexane layer at the end of the Group I anion experiment?

(when color of hexane layer is yellow you have Br- and when it is brown or purple you have I-.) please explain

During the Group I anion experiment, different halide ions (such as Br- and I-) are separated and identified using organic solvents like hexane. In this experiment, a sample containing an unknown halide ion is treated with specific reagents to form a colored organic layer in hexane, which indicates the presence of a particular halide ion.

In the case of Br-, when the hexane layer turns yellow, it signifies the presence of this halide ion. This color change occurs due to the formation of an organic complex called dibromo-diphenylcarbazone (DBDC) when bromide ions react with an organic reagent.

When it comes to the presence of I-, the hexane layer will turn brown or purple. This color change indicates the formation of an organic complex known as starch-iodine complex. Iodide ions react with iodine to form this complex, resulting in the change in color.

Therefore, by observing the color change in the hexane layer after specific reactions with the unknown halide ions, it is possible to identify whether Br- or I- ions are present in the sample.

In the Group I anion experiment, a mixture of different anions such as chloride (Cl-), bromide (Br-), and iodide (I-) is tested to identify which anions are present. To determine the presence of bromide or iodide ions, the hexane layer is crucial.

In this experiment, a solution containing the anions is first extracted with an organic solvent called hexane. This extraction process helps separate the anions based on their solubility in different solvents.

When the hexane layer turns yellow, it indicates the presence of bromide ions (Br-). Bromide ions react with a solution of hexane and a reagent called chloroform (CHCl3) to form an organic compound called ethyl bromide (C2H5Br). Ethyl bromide has a yellow color, which imparts the yellow hue to the hexane layer.

On the other hand, when the hexane layer becomes brown or purple, it suggests the presence of iodide ions (I-). Iodide ions react with a solution of hexane and chloroform to produce a different organic compound called ethyl iodide (C2H5I). Ethyl iodide has a brown or purple color, which leads to the change in color of the hexane layer.

In summary, the change in color of the hexane layer at the end of the Group I anion experiment indicates the presence of specific anions. When it is yellow, it signifies the presence of Br-, while brown or purple suggests the presence of I-. These color changes occur due to the formation of specific organic compounds (ethyl bromide or ethyl iodide) during the chemical reaction between the anions and the solvent system.

This question is too vague for me to answer. I don't know what you are looking for in an answer. Perhaps something about Dispersion forces (instantaneous dipole-induced dipole) which is responsible for the violet color (and for the yellow color of the Br^-). By the way, I wouldn't expect a brownish color to indicate iodine unless the hexane layer was contaminated with some water or alcohol.