REVISAO ENEM - METAL DE SACRIFICIO

Electrochemistry is one of the most frequently addressed topics in various university entrance exams (ENEM, UNICAMP, FUVEST, UFSC, UECE...) we should always review this subject!!! (ENEM PPL 2019) Some coins use metallic copper in their composition. This metal, when exposed to humid air in the presence of CO₂, undergoes oxidation forming verdigris, a basic carbonate with the formula Cu₂(OH)₂CO₃, which is toxic to humans and, therefore, is characterized as an environmental pollutant. In order to reduce contamination with verdigris, decrease manufacturing costs, and increase the durability of coins, it is common to use alloys resulting from the association of copper with another metallic element. The property that the metal associated with copper must present to prevent the formation of verdigris in coins is, in relation to copper, a) greater acidic character. b) higher oxidation number. c) lower reduction potential. d) lower reactivity. e) fewer electrons in the valence shell.