Question

Describe two chemical differences between \(\mathrm{CO}\) and \(\mathrm{CO}_{2}\).

Short answer

\(\mathrm{CO}\) has a triple bond and is polar, while \(\mathrm{CO}_{2}\) has double bonds and is non-polar.

Step-by-step solution

Determine the Molecular Structure

First, examine the molecular structure of the compounds. Carbon monoxide (\(\mathrm{CO}\)) consists of one carbon atom triple-bonded to one oxygen atom. In contrast, carbon dioxide (\(\mathrm{CO}_{2}\)) is composed of one carbon atom double-bonded to two oxygen atoms, forming a linear structure.

Analyze Bonding and Valency

Consider the bonding and valency in each molecule. In \(\mathrm{CO}\), a triple bond between carbon and oxygen implies that there are shared electrons providing stability to the compound, but due to uneven valency satisfaction, \(\mathrm{CO}\) has a lone pair on carbon. In \(\mathrm{CO}_{2}\), the double bonds fully satisfy the valency requirements of both carbon and oxygen, leading to a stable electron distribution without lone pairs on the carbon atom.

Compare Polarity

Examine the polarity of each molecule. \(\mathrm{CO}\), due to its triple bond and the difference in electronegativity between the atoms, exhibits a polar characteristic along the bond. However, \(\mathrm{CO}_{2}\) is non-polar overall, despite the polar nature of the individual \(\mathrm{C=O}\) bonds, because the linear geometry causes the dipole moments to cancel each other out.

Key concepts

Molecular Structure

The molecular structure of compounds provides crucial information about how atoms are connected within a molecule, affecting everything from reactivity to physical properties. Carbon monoxide (\(\mathrm{CO}\)) and carbon dioxide (\(\mathrm{CO}_{2}\)) have distinct structural differences. In \(\mathrm{CO}\), you find one carbon atom triple-bonded to an oxygen atom. This strong triple bond means a short bond length and high bond energy, leading to a linear but simple structure.
On the other hand, \(\mathrm{CO}_{2}\) consists of one carbon atom double-bonded to two oxygen atoms. This configuration results in a linear molecular shape due to the nature of double bonds. The double bonds are longer compared to triple bonds, altering the molecule's properties in terms of reactivity and bonding nature significantly.

• \(\text{CO:}\) Triple bond, linear, one oxygen
• \(\text{CO}_{2}:\) Double bonds, linear, two oxygens

Understanding these differences helps in predicting molecule behavior in reactions and interactions with other substances.

Valency

Valency relates to an atom's capacity to bond with other atoms, determined by the number of valence electrons. In carbon monoxide (\(\mathrm{CO}\)), we observe that carbon and oxygen are linked by a triple bond. This bond doesn't completely satisfy the valency of carbon, leading to the presence of unshared electrons (a lone pair) on the carbon. This situation can impact the molecule's stability and reactivity.
In carbon dioxide (\(\mathrm{CO}_{2}\)), each carbon-oxygen link is a double bond. These double bonds satisfy the valency requirements of both carbon and oxygen fully. There are no lone pairs on the carbon atom, which implies a symmetric distribution of electrons within the molecule and greater stability.

• \(\text{CO:}\) Triple bond, lone pair on carbon, partially satisfied valency
• \(\text{CO}_{2}:\) Double bonds, full valency satisfaction, stable

Understanding valency is key to grasping how molecules form, react, and achieve stability.

Molecular Polarity

Molecular polarity arises from differences in electronegativity between bonded atoms and the molecular geometry. Carbon monoxide (\(\mathrm{CO}\)) is a prime example, as it features a region of partial negative charge on the oxygen due to the oxygen's higher electronegativity compared to carbon. This creates a dipole, leading \(\mathrm{CO}\) to be polar.
In carbon dioxide (\(\mathrm{CO}_{2}\)), however, the molecule consists of two polar \(\mathrm{C=O}\) bonds. Yet, due to its linear geometry, the polarities of these bonds cancel each other out, resulting in an overall non-polar molecule. This unique feature of \(\mathrm{CO}_{2}\) emphasizes how molecular geometry plays a pivotal role in determining polarity.

• \(\text{CO:}\) Polar due to electronegativity difference
• \(\text{CO}_{2}:\) Non-polar due to linear cancellation of bond polarities

Recognizing polarity helps in predicting molecule interactions, solubility, and how they may behave in electric fields.