(a) Write a balanced equation for the production of 2,3 -dibromobutane from 2-butyne. (b) What name is given to this type of reaction?

Balancing chemical equations is a fundamental skill in chemistry that ensures the Law of Conservation of Mass is upheld, meaning that the mass of the reactants must equal the mass of the products in a chemical reaction. In a balanced chemical equation, the number of atoms for each element is the same on both sides of the equation.

Let's apply the concept of balancing to the production of 2,3-dibromobutane from 2-butyne. Initially, the chemical equation appears as: \( C_4H_6 + Br_2 \rightarrow C_4H_8Br_2 \). To balance it, we compare and adjust the number of each type of atom on both sides of the equation. Here, the carbons (C) are balanced with four on each side; the hydrogens (H) are balanced too, with six on the reactant side and eight on the product side after halogenation. Lastly, we see two bromine (Br) atoms are added during the reaction, and to reflect this, we include one molecule of bromine (\(Br_2\)) in the reactants.

Our final balanced chemical equation correctly represents both the reactants and products while respecting the conservation of mass principle: \( C_4H_6 + Br_2 \rightarrow C_4H_8Br_2 \).

Alkynes are hydrocarbons with at least one carbon-carbon triple bond and they undergo a variety of chemical reactions, most notably addition reactions. The triple bond in alkynes has two pi bonds and one sigma bond, making it quite reactive. In an alkyne reaction, such as the formation of 2,3-dibromobutane from 2-butyne, the electrons in the pi bonds are available for reactions with electrophiles, like bromine.

During the halogenation of 2-butyne, each bromine atom forms a new bond with the carbon atoms in the triple bond. This transforms the triple bond into a single bond, and thus, the alkyne becomes a dihaloalkane. This reaction is an example of how the reactivity of alkynes is harnessed to produce more complex molecules.

Addition reactions occur when two or more reactants combine to form a single product. This type of reaction is prevalent with unsaturated molecules, such as alkenes and alkynes, which have double or triple bonds, respectively. The halogenation of an alkyne, such as 2-butyne, to form 2,3-dibromobutane is a perfect demonstration of an addition reaction.

In the given exercise, bromine adds across the carbon-carbon triple bond of 2-butyne. The pi bonds of the alkyne are broken and replaced with two new carbon-bromine sigma bonds. The end result is that the alkyne has become 'saturated' with bromine atoms. Addition reactions, like this halogenation, are a pivotal class of reactions in organic chemistry that help in building complex structures from simpler ones.