(Originais Teachy 2023) - Question Very Hard of Chemistry

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.

A chemical reaction A + 2B -> C + D occurs in a system where the initial concentrations of A and B are, respectively, 0.1 mol/L and 0.2 mol/L. After a period of time, the concentration of A decreased to 0.05 mol/L. Considering that the reaction is first order with respect to A and second order with respect to B, determine the overall order of the reaction and explain how you reached this conclusion.

In the pharmaceutical sector, the development of a new medication involves using acyl halide as an active intermediate. Considering how acyl halides compare with carboxylic acids, which of the following reasons supports the choice of acyl halide for this chemical procedure?