Question

Post Lab Questions 1. Explain the chemical difference between direct dyes and ingrain dyes. 2. Draw the diazonium salt produced when sulfanilic acid is reacted with sodium nitrite and hydrochloric acid. Next draw the dye that is produced when the diazonium salt is reacted with the 2-naphthol anion. What is the name of this dye? 3. Which direct dyeing procedure worked best for Orange I1? Briefly explain. 4. Compare ing rain dyeing and direct dyeing with Orange II. Which worked better? Purpose a reason for this result. 5. Complete the table with the comparative effects sodium hypochlorite and sodium hydrosulfite have on each the dyed cotton strips.

Answer 1

1. The colored substances that bind the substrate chemically is known as dyes. Dyes generally applied to substrate in aqueous solution. The classification of dyes is done on the basic of the structure of the dyes and application of dyes.

Ingrain dyes are azo dyes that contains azo groups as the chromophore whereas direct dyes are sodium salt of sulphonic acid and contains azo groups as the main chromophore. The examples of both the dyes are shown below.

Azo group Azo group ОН Azo group iz (Direct dyes) -NEN -NH2 6 . p-amino azobenzene (Ingrain dyes) Sodium salt of sulphonic acid