structures

Methyl Orange is an acid-base indicator. In dilute solution at pH greater than 4.4, it is yellow. At pH=3.2 the solution appears red. Draw a structure of the species that is formed at the lower pH of the acid proton adds to the azo nitrogen atom adjacent to the aromatic ring containing the -SO3 group. Why does the proton add to this particular nitrogen when two other nitrogen atoms are available in the molecule?

mechanisms

Benzene is brominated in the presence of FeBr3 catalyst. Suggest an appropriate mechanism for this reaction.

pH of a solution

In an experiment, a point is made that the formation of the azo compound is a slow reaction, but that rate is increased by raising the pH of the solution. Why is this necessary? In other words, how does the pH of the solution affect the reactivity of the N,N-dimethylaniline reagent.

pH of a solution

Diazonium salts couple with phenols in slightly alkaline solution. What effect does the pH of the solution have on the reactivity of the phenol?

balanced equations

In an experiment, sodium bisulfite solution is added at the end in order to destroy the unreacted bromide. What reaction is occuring here? Is HSO3- acting as an oxidizing or reducing agent? Write a balanced equation as part of your answer.