The hydrogenation of alkenes is a chemical process that involves the addition of hydrogen to a carbon-carbon double bond, resulting in the formation of an alkane.

Hydrogenation is defined as a chemical reaction where molecular hydrogen ($H_2$) is added to a compound. In the context of alkenes, this process specifically targets the carbon-carbon double bond, ultimately converting the alkene into an alkane. Typically, this reaction is accelerated by a catalyst, commonly a metal such as nickel, palladium, or platinum.

As an addition reaction, the hydrogenation of alkenes represents a fundamental type of reaction in organic chemistry. In an addition reaction, new atoms or groups of atoms are incorporated into a molecule, which often leads to the breaking of existing double bonds. During the hydrogenation of alkenes, the carbon-carbon double bond is cleaved, and a hydrogen atom is added to each carbon atom involved.

This reaction can be summarized by the equation:

For instance, when ethene ($C_2H_4$) undergoes hydrogenation, it is transformed into ethane ($C_2H_6$). This transformation can be expressed as:

Hydrogenation is extensively utilized in the food industry, particularly to convert unsaturated fats into saturated fats, which are typically solid at room temperature. This process is the basis for transforming vegetable oils into margarine. However, it is important to note that hydrogenation can lead to the formation of trans fats, which have been associated with various health issues.

In conclusion, the hydrogenation of alkenes is a chemical reaction that adds hydrogen to a carbon-carbon double bond, yielding an alkane. This process is facilitated by a catalyst and exemplifies the characteristics of addition reactions in organic chemistry.