Question

In terms of numbers of reactant and product substances, which organic reaction type corresponds to (a) a combination reaction, (b) a decomposition reaction, (c) a displacement reaction?

Short answer

(a) Combination: joining reactants to form one product, (b) Decomposition: breaking one reactant into multiple products, (c) Displacement: replacing part of the molecule.

Step-by-step solution

Identify Combination Reaction

In a combination reaction, two or more reactants combine to form a single product. In organic chemistry, this could mean the formation of a larger molecule from smaller ones. For example, the formation of an ester from an alcohol and a carboxylic acid is a combination reaction.

Identify Decomposition Reaction

A decomposition reaction involves breaking down one compound into two or more simpler substances. In organic reactions, such a process could be represented by the breakdown of a compound like an ester into an alcohol and a carboxylic acid when hydrolysis occurs.

Identify Displacement Reaction

A displacement reaction occurs when an atom or a group of atoms in a molecule is replaced by another atom or group of atoms. An example would be the reaction of an alkyl halide with a nucleophile where the halide is replaced by the nucleophile, forming a new compound and releasing the halide.

Key concepts

Combination Reaction in Organic Chemistry

Combination reactions, also known as synthesis reactions, occur when two or more reactants combine to form a single product. This type of reaction is essential in organic chemistry, allowing the formation of complex molecules from simpler ones. For instance, when an alcohol reacts with a carboxylic acid, they combine to form an ester. This reaction is typically represented as:

• Reactants: Alcohol (R-OH) and Carboxylic Acid (R-COOH)
• Product: Ester (R-COOR) and Water (H2O)

These reactions are crucial in organic synthesis and are used to create a variety of compounds, from pharmaceuticals to polymers. Remember, the defining feature of a combination reaction is that multiple reactants form a single product.

Decomposition Reaction in Organic Chemistry

Decomposition reactions involve the breakdown of a single compound into two or more simpler substances. In organic chemistry, these reactions are often encountered during the breakdown of complex molecules into their basic components. For example, an ester undergoing hydrolysis can decompose into an alcohol and a carboxylic acid. This reaction is expressed as:

• Reactant: Ester (R-COOR)
• Products: Alcohol (R-OH) and Carboxylic Acid (R-COOH)

Such reactions are essential in biochemistry, industrial processes, and environmental systems as they help in recycling and breaking down organic materials. A key aspect to note is that a single reactant is converted into multiple products.

Displacement Reaction in Organic Chemistry

A displacement reaction involves an atom or a group of atoms in a molecule being replaced by another atom or group of atoms. This type of reaction is crucial in organic chemistry for forming new compounds. For example, in the reaction of an alkyl halide with a nucleophile, the halide (often a chloride or bromide) is replaced by the nucleophile, forming a new product. This reaction can be seen as:

• Reactants: Alkyl Halide (R-X) and Nucleophile (Nu-)
• Products: New Compound (R-Nu) and Halide Ion (X-)

Displacement reactions are foundational in synthetic organic chemistry, aiding in creating a wide variety of chemicals. The key detail is that one part of the molecule is replaced by another, facilitating the creation of new functional groups and compounds.