1-bromobutane will undergo reactions when heated, as shown by reactions A and B. For reactions A and B give the reagents used in each case.

B = aqueous sodium hydroxide (solution)

1-bromobutane will undergo reactions when heated, as shown by reactions A and B. Reaction A was repeated using 1-iodobutane instead of 1-bromobutane. Explain any difference in the rate of reaction observed.

Reaction is faster with 1-iodobutane .When reaction A is repeated using 1-iodobutane instead of 1-bromobutane, the rate of reaction becomes faster. ■ the fastest nucleophilic substitution reactions take place with the iodoalkanes ■■ the slowest nucleophilic substitution reactions take place with the fluoroalkanes. The substitution reaction involves the breaking of the carbon halogen bond. The C–I bond is the weakest, so it is broken most easily. It forms an I - ion during the substitution reaction when reaction A is repeated using 1-iodobutane instead of 1-bromobutane. Hence, as C–I bond is weaker than C–Br bond, so the former is broken more easily. When an aqueous solution of sodium hydroxide is added to a halogenoalkane, a nucleophilic substitution reaction takes place. The halogen atom in the halogenoalkane is replaced by an OH, hydroxyl group, so the organic product formed is an alcohol The aqueous hydroxide ion behaves as a nucleophile here, because it is donating a pair of electrons to the carbon atom bonded to the halogen in the halogenoalkane. This is why the reaction is called a nucleophilic substitution.