Step into the Generalities in Chemistry, where the foundations of this diverse field are explored. Delve into the fundamental principles and concepts that underpin the study of matter and its transformations. From atomic structure and chemical bonding to states of matter and chemical reactions, uncover the key elements that shape our understanding of chemistry. Embark on a journey of discovery as you unravel the secrets and intricacies of this fascinating science.
Food additives are assigned a code in the EU called “E-numbers” (the E for Europe). These are codes for substances used as food additives for use within the EU and the European Free Trade Association (EFTA). Commonly found on food labels, their evaluation and safety approval is the responsibility of the European Food Safety Authority … Read more
What is the Lewis acid-base theory? In 1923, Lewis proposed a theory to explain the behavior of acidic and basic substances. This is because previous theories, such as Brønsted-Löwry, defined them in terms of proton acceptance/transfer (H⊕). However, substances were known which, lacking hydrogen in their molecule, such as SO3 and CO2, behave as acids. … Read more
What is hydrolysis? Literally hydrolysis means breakage by water. We know that when an acid and a base react with each other a salt plus water is formed: AH +BOH <–> AB + H2O It is conceivable that if the process is reversible, i.e., that when a salt dissolves in water, an acid or base may appear … Read more
What is bond polarity? Bond polarity can be defined as the difference in electronegativity (δEN) between the two bonding atoms. The greater the difference in electronegativity, the more polar the bond. Types of bonds If a bond is formed by two equal atoms (same electronegativity) it gives rise to a covalent bond, they share electrons … Read more
What is the Arrhenius acid-base theory? Acids: substances that in aqueous solution dissociate by yielding protons (H+). Acids: sustancias que en disolución acuosa se disocian cediendo protones (H+). Bases: substances that in aqueous solution dissociate by yielding hydroxide ions (OH–). Salts: substances that in aqueous solution dissociate by yielding other ions. In general the dissociation equations are: … Read more
What is the Brønsted-Löwry acid-base theory? In 1938, Brønsted and Löwry improved the Arrhenius acid-base theory and classified acidic and basic compounds as follows: Acid: substance (molecular or ionic) capable of donate protons (H+) to another substance acting as a base. Base: substance (molecular or ionic) capable of accepting protons (H+) from an acid. According … Read more
What is a pH buffer solution? The mission of the pH buffer solutions is to maintain the pH of the solution containing them invariable (constant) in the against of dilutions and addition of acids or bases. These solutions are made up of mixtures of: -Weak acid + salt of weak acid-strong base: CH3COOH + CH3COONa … Read more
What is osmolar concentration? Osmolarity is a concept related to solutions that indicates the osmolar concentration, defined as the number of osmoles per liter of solution. Osmol means the number of particles in the molecular weight of undissociated solute. Examples Glucose (does not dissociate) : 1 osmol = 1 mole = 180 gr of glucose … Read more
What are acids and bases? In the past, scientists classified the then known substances into acids, bases and salts. In principle, they classified them according to a series of similar properties. In 1663 Robert Boyle established a series of properties common to all acids. Thus, an acid was defined as a substance whose aqueous solution: … Read more
What is an enantiomer? An enantiomer refers to two structures that are mirror images but not superimposable. The term comes from the Greek enántios, “opposite”, and méros, “part” or “portion”. They are also called optical isomers. Characteristics The main characteristic of two enantiomers is that all their physicochemical properties are the same except that they … Read more
