The foul odor of rancid butter is caused by butyric acid, \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\) (a) Draw the Lewis structure and determine the oxidation number and hybridization for each carbon atom in the molecule. (b) The esters formed from butyric acid are pleasant-smelling compounds found in fruits and used in perfumes. Draw the Lewis structure for the ester formed from the reaction of butyric acid with 2 -propanol.

Understanding the Lewis structure is fundamental in grasping basic chemistry concepts. Lewis structures are diagrams that represent the bonds between atoms of a molecule and the lone pairs of electrons that may exist. For butyric acid (\(CH_3CH_2CH_2CO_2H\)), we depict the connectivity of atoms with straight lines representing bonds and dots for lone electron pairs. The carbon atoms are arranged in a chain, with hydrogen atoms filling the valence of carbon to complete the octets, while the carboxylic group (\(CO_2H\)) displays a double bond between the carbon and one oxygen atom. This detailed depiction helps us visualize the molecule's structure and lays the groundwork for understanding more complex chemical properties.

Diving into oxidation numbers, it's important to clarify that they indicate the degree of oxidation of an atom in a compound. Essentially, they are bookkeeping numbers that provide insight into the transfer of electrons during chemical reactions. For butyric acid's differing carbon atoms, it's a game of counting: each \(C-H\) bond bestows upon carbon a -1, while bonds with more electronegative atoms like oxygen give carbon a +1. By following these rules, we assign the distinctive oxidation states to each carbon atom in the chain of butyric acid, helping to predict reactivity and providing a solid foundation for understanding chemical changes.

Exploring hybridization opens a window into the fascinating world of atomic orbitals. This concept explains the combination of atomic orbitals to form new hybrid orbitals, which then host the electron pairs involved in chemical bonding. The spacial arrangement of these bonds and lone pairs, termed as the steric number, determines the hybridization state. In butyric acid, the \(CH_3\) and \(CH_2\) carbon atoms are associated with sp^3 hybridization due to their tetrahedral arrangement from the four single covalent bonds. In contrast, the carboxyl group's carbon, with sp^2 hybridization, reveals a trigonal planar arrangement with one double bond and two single bonds. Understanding hybridization offers a 3D perspective on molecules and is vital for comprehending their physical and chemical properties.

The process of ester formation is a delightful journey from foul to fragrant. Esters are the compounds responsible for the fruity scents and flavors. The transformation from butyric acid to a pleasant ester occurs when it reacts with an alcohol — specifically, 2-propanol in our case. The ester is formed by connecting the carbonyl carbon of butyric acid to the oxygen of 2-propanol, replacing the acid's hydroxyl group and the hydrogen from the alcohol's hydroxyl group. This reaction forms water and results in the creation of an ester linkage (\(COO\)). Visualizing the structured Lewis diagram of this process allows students to see the beauty in chemistry and appreciate the versatility of organic compounds.

Finally, let's piece together the transformative esterification process, where acids and alcohols combine to yield sweet-smelling esters. This intricate dance involves the removal of water — dehydration — to link an acid's carbonyl group to an alcohol's oxygen atom. It's a two-step tango: first, the acid's hydroxyl group aligns with the alcohol's hydrogen, preparing to exit stage-left as water. Second, the new duo — the acid's carbonyl carbon and the alcohol's oxygen — forms a bond to complete the ester group. The result? A pleasing ester with unique aromatic attributes and a clear depiction of the magic that is organic chemistry.