(Originais Teachy 2023) - Question Medium of Chemistry

Identify the organic function present in the ester of molecular formula C4H8O2 that is responsible for the aroma of a fruit. Consider that the ester has a carbon chain of 3 carbon atoms and a radical from a monocarboxylic acid of general formula CnH2nO2. Name the monocarboxylic acid and the alcohol used in the synthesis of this ester, following the IUPAC nomenclature rules for organic compounds. Justify the choice of the acid and the alcohol based on the structure and the desired aroma.

When studying covalent bonds, 1st-year high school students learned about Lewis theory, which describes the formation of covalent bonds through the sharing of electron pairs between atoms. Considering that the covalent bond is formed between two non-metals, propose and explain an example of a covalent compound, highlighting its structural formula and how Lewis theory can be applied to describe the formation of covalent bonds in the chosen compound. Additionally, briefly discuss a characteristic physical or chemical property of this type of covalent compound that differentiates it from ionic or metallic compounds.

The German chemist Friedrich August Kekulé was very important for the development of organic chemistry by presenting his postulates on the structure of organic compounds in the 19th century. One of his most important postulates is the tetravalence of carbon. Considering the concept of tetravalence and covalent bonds in organic molecules, answer the following questions: a) Explain why carbon is tetravalent, and briefly describe the relationship of this concept with covalent bonds. b) Give examples of three organic compounds that have tetravalent carbon and their respective structural formulas. c) Describe how the postulate of carbon tetravalence was fundamental for understanding the structures of organic compounds in Kekulé's time and, consequently, how it influenced organic chemistry in general.