(Originais Teachy 2023) - Question Easy of Chemistry

A chemical equation is a mathematical equation that represents an equality: all atoms and their quantities that appear in the reactants must also be present in the products. Considering a chemical equation and its corresponding equilibrium constant, it can be correctly stated that, by multiplying all its coefficients by 2, the equilibrium constant associated with this new equation will be

A chemical laboratory received a sample of a new metallic oxide, and the scientists must determine the chemical formula of the compound based on its properties. The sample reacts with water, forming an acid that, when analyzed, reveals the presence of hydrogen and a metal that behaves as a divalent metal in its reactions. Additionally, the sample reacts with diluted hydrochloric acid, forming a metal chloride and water. If the mass of the metal present in the sample is 27g, determine the chemical formula of the metallic oxide and explain the reasoning used, including the nomenclature of the compounds found.

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.

Consider a salt that undergoes hydrolysis in water, producing a weak acid and a weak base. How to determine if the final solution will be acidic or basic? How to calculate the final concentration or pH of the resulting solution? Give an example of a salt and calculate the pH of the resulting solution.