Question

If you used a bromine test to distinguish between hexane and 2-hexene, in which would th red color of the bromine persiste?

Answer 1

In a bromine test, the red color would persist in hexane as it is a saturated compound and does not react with bromine, while it would disappear in 2-hexene, which contains a double bond and undergoes halogenation.

Step-by-step explanation:

The bromine test is a qualitative assay in organic chemistry for the presence of unsaturation, particularly double bonds in alkenes. When bromine solution, which is brownish-red in color, is added to an alkene such as 2-hexene, the color of the solution disappears as the alkene reacts with the bromine to form a colorless dibromoalkane. This happens because alkenes readily undergo halogenation. In contrast, hexane is a saturated alkane and does not react with bromine; hence in hexane, the red color of bromine would persist. This test is useful for distinguishing between unsaturated and saturated hydrocarbons. When using bromine to differentiate hexane and 2-hexene, the red color would remain in the hexane sample since it is saturated and does not react with bromine.

Answer 2

Explanation;

Bromine test is done to distinguish between the unsaturated hydrocarbons from saturated hydrocarbons.

When we add bromine water to an unsaturated hydrocarbon ,bromine atoms get attached to the carbons with double bond in between. This reaction between bromine water and unsaturated hydrocarbon results in de-colorization of bromine water color from red to colorless.

When bromine water is added to hexane no color change will be observed.

`C_6H_(14)+Br_2\rightarrow` no reaction

When bromine water is added to 2-hexene color change will be observed.

`CH_3-CH=CH-C_3H_7+Br_2\rightarrow CH_3-CHBr-CHBr-C_3H_7`