The unsaturated compounds having double or triple bonds under go the addition reactions with Bromine water, ethanol does not have the double or triple bonds
When bromine water is added to ethanol, the bromine will react with the ethanol forming 2-bromoethanol. The reaction occurs via nucleophilic substitution where the bromine reacts with the -OH group of ethanol. This reaction can be used as a test to distinguish between primary, secondary, and tertiary alcohols.
Hexane and bromine water do not react with each other. However, sodium hydroxide solution can react with hexane through a process called saponification to form soap, but it does not react with bromine water.
Salicylic acid does not react with bromine water under normal conditions. However, if heated, bromine may react with salicylic acid to form 2,3-dibromosalicylic acid.
When bromine water is shaken with a saturated fat, the bromine water will turn colorless. This is because saturated fats do not contain double bonds to react with the bromine in a typical alkene addition reaction, which would normally turn the bromine water brown/orange.
Bromine water fades when testing for saturation because the bromine is decolorized by the unsaturated organic compounds present in the solution. This reaction occurs because the unsaturated compounds react with and break the bromine-bromine bond, causing the bromine solution to lose its color.