Acetylene (C2 H2) and nitrogen (N2) both contain a triple bond, but they differ greatly in their

step 1 we will be considering the compound chloral hydrate. This is a substance that is commonly known

Acetylene (C2 H2) and nitrogen (N2) both contain a triple...

Acetylene $\left(\mathrm{C}_{2} \mathrm{H}_{2}\right)$ and nitrogen $\left(\mathrm{N}_{2}\right)$ both contain a triple bond, but they differ greatly in their chemical properties. (a) Write the Lewis structures for the two substances. (b) By referring to Appendix $C$, look up the enthalpies of formation of acetylene and nitrogen and compare their reactivities. (c) Write balanced chemical equations for the complete oxidation of $\mathrm{N}_{2}$ to form $\mathrm{N}_{2} \mathrm{O}_{5}(g)$ and of acetylene to form $\mathrm{CO}_{2}(g)$ and $\mathrm{H}_{2} \mathrm{O}(g)$ (d) Calculate the enthalpy of oxidation per mole of $\mathrm{N}_{2}$ and $\mathrm{C}_{2} \mathrm{H}_{2}$ (the enthalpy of formation of $\mathrm{N}_{2} \mathrm{O}_{5}(g)$ is $11.30 \mathrm{~kJ} / \mathrm{mol}$ ). How do these comparative values relate to your response to part (b)? Both $\mathrm{N}_{2}$ and $\mathrm{C}_{2} \mathrm{H}_{2}$ possess triple bonds with quite high bond enthalpies (Table 8.4). What aspect of chemical bonding in these molecules or in the oxidation products seems to account for the difference in chemical reactivities?

Acetylene $\left(\mathrm{C}_{2} \mathrm{H}_{2}\right)$ and nitrogen $\left(\mathrm{N}_{2}\right)$ both contain a triple bond, but they differ greatly in their chemical properties. (a) Write the Lewis structures for the two substances. (b) By referring to Appendix $C$, look up the enthalpies of formation of acetylene and nitrogen and compare their reactivities. (c) Write balanced chemical equations for the complete oxidation of $\mathrm{N}_{2}$ to form $\mathrm{N}_{2} \mathrm{O}_{5}(g)$ and of acetylene to form $\mathrm{CO}_{2}(g)$ and $\mathrm{H}_{2} \mathrm{O}(g)$
(d) Calculate the enthalpy of oxidation per mole of $\mathrm{N}_{2}$ and $\mathrm{C}_{2} \mathrm{H}_{2}$ (the enthalpy of formation of $\mathrm{N}_{2} \mathrm{O}_{5}(g)$ is $11.30 \mathrm{~kJ} / \mathrm{mol}$ ). How do these comparative values relate to your response to part (b)? Both $\mathrm{N}_{2}$ and $\mathrm{C}_{2} \mathrm{H}_{2}$ possess triple bonds with quite high bond enthalpies (Table 8.4). What aspect of chemical bonding in these molecules or in the oxidation products seems to account for the difference in chemical reactivities?

Key Concepts

Balanced Chemical Equations

Balanced chemical equations accurately represent chemical reactions by showing equal numbers of atoms for each element on both sides of the reaction. They are essential for determining stoichiometric relationships, calculating reaction energies, and ensuring that conservation laws are followed in any reaction analysis.

Lewis Structures

Lewis structures are diagrams that depict the arrangement of valence electrons in molecules. They are used to represent chemical bonding and the distribution of electrons among atoms, helping to predict molecular geometry, reactivity, and the presence of lone pairs or multiple bonds.

Triple Bonds

Triple bonds involve three pairs of electrons shared between two atoms, typically leading to shorter, stronger bonds compared to single or double bonds. They play a central role in determining the stability and reactivity of molecules by influencing bond lengths, bond strengths, and the overall electronic structure.

Enthalpy of Formation

The enthalpy of formation is the heat change that occurs when one mole of a compound is formed from its elements in their standard states. This thermodynamic quantity provides insight into the stability of a compound; substances with highly negative enthalpies tend to be more stable and less reactive.

Bond Enthalpy

Bond enthalpy refers to the energy required to break a particular bond in one mole of gaseous molecules. It is a quantitative measure of bond strength and helps in predicting the energy changes during chemical reactions, particularly in comparing how different bonds affect a molecule's reactivity.

Oxidation Reactions

Oxidation reactions involve the loss of electrons, typically through the reaction with oxygen, leading to the formation of products like carbon dioxide or higher oxides. In the context of combustion or oxidation, balanced chemical equations are used to represent these processes, ensuring the conservation of mass and energy.

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