Problem 67 - Chemistry and Chemical Reactivity

Question

Give the bond order of each bond in acetylene, \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H},\) and phosgene, \(\mathrm{Cl}_{2} \mathrm{CO}\).

Step-by-Step Solution

Answer

Acetylene: C-H (1), C≡C (3); Phosgene: Cl-C (1), C=O (2).

Step 1: Understanding Bond Order

Bond order is the number of chemical bonds between a pair of atoms. For example, in a single bond, such as \( ext{C-H}\), the bond order is 1. In a double bond, such as \( ext{C=O}\), the bond order is 2, and in a triple bond, such as \( ext{C} ext{≡} ext{C}\), the bond order is 3.

Step 2: Determine Bond Order in Acetylene

Acetylene \(\text{H-C} \equiv \text{C-H}\) has a single bond between hydrogen and carbon (\(\text{C-H}\)), resulting in a bond order of 1. The bond between the two carbon atoms is a triple bond (\(\text{C} \equiv \text{C}\)), resulting in a bond order of 3.

Step 3: Determine Bond Order in Phosgene

Phosgene, which has the structure \(\text{Cl}_{2}\text{CO}\), includes two single bonds between chlorine and carbon (\(\text{Cl-C}\)), each having a bond order of 1, and a double bond between carbon and oxygen (\(\text{C=O}\)), with a bond order of 2.

Key Concepts

Understanding Chemical Bonds

Chemical bonds form when atoms attach to each other to create molecules. These bonds involve the sharing or transferring of electrons to attain a more stable electronic configuration. There are three primary types of chemical bonds:

• Single Bond: A single bond, like in hydrogen chloride (HCl), shares one pair of electrons, resulting in a bond order of 1.
• Double Bond: A double bond, as seen in molecules like carbon dioxide (CO extsubscript{2}), involves two shared pairs of electrons and has a bond order of 2.
• Triple Bond: A triple bond shares three pairs of electrons, like in nitrogen gas (N extsubscript{2}), and has a bond order of 3.

The bond order directly correlates with bond strength, length, and stability. Generally, a higher bond order means a stronger and shorter bond. Understanding bond order helps predict the properties and reactivity of molecules.

Acetylene Molecule

Acetylene is a simple alkyne with the chemical formula H-C≡C-H. It plays a significant role in industrial and organic chemistry. Its structure can be visualized as being linear, involving sp hybridization.

• The terminal C-H bonds in acetylene are single bonds, each having a bond order of 1.
• The central C≡C bond is a triple bond, holding a bond order of 3. This triple bond is composed of one sigma bond and two pi bonds.

The presence of a triple bond makes acetylene quite a reactive molecule. It serves as a foundational compound for many chemical reactions, notably in polymerizations and synthesis of chemicals. The acetylene molecule illustrates how multiple bonds can impact bond length and molecular properties.

Phosgene Characteristics

Phosgene, with a chemical formula of Cl extsubscript{2}CO, is a colorless gas at room temperature. It is known for its use in chemical manufacturing and notably during World War I as a chemical weapon. Phosgene has a trigonal planar structure and is important in organic chemistry.

• The Cl-C bonds in phosgene are single bonds, giving them a bond order of 1.
• The C=O bond is a double bond, having a bond order of 2 due to the sharing of two pairs of electrons.

Phosgene's structure is relatively stable, although the molecule is highly reactive with water, forming carbon dioxide and hydrochloric acid. Understanding the bond orders in phosgene allows chemists to predict its reactions and adhere to safe handling practices, especially in the industry where it's most prevalent.