Binary Acids vs Oxyacids
Acids are defined in several ways by various scientists. Arrhenius defines an acid as a substance that donates H3O+ ions in the solution. Bronsted- Lowry defines a base as a substance that can accept a proton. Lewis acid definition is far common than the above two. According to it, any electron pair donator is a base. According to the Arrhenius or Bronsted-Lowry definition, a compound should have a hydrogen and the ability to donate it as a proton to be an acid. But according to Lewis, there can be molecules, which don’t possess hydrogen, but can act as an acid. For example, BCl3 is a Lewis acid, because it can accept an electron pair. An alcohol can be a Bronsted-Lowry acid, because it can donate a proton; however, according to Lewis, it will be a base. Regardless of the above types of acids which are defined differently, acids can be described and classified in many other ways. For example, acids are classified as inorganic and organic acids depending on the elements they have. In this article, we are going to focus on another way of classifying acids, which is as binary acids and oxyacids.
Binary acids are molecules, which contain two elements; one element is hydrogen, and the other one is a nonmetal element, which is more electronegative than hydrogen. Therefore, binary acids can donate H+ ions in aqueous media. HCl, HF, HBr, and H2S are some of the examples for binary acids. These show different properties when they are in pure form and when they are in aqueous media. In the nomenclature of binary acids, if the acid is in the pure form, the name starts with “hydrogen” and the anionic name ends with “-ide”. For example, HCl is named as hydrogen chloride. Aqueous binary acid solution names are starting with “hydro”, and the anion name ends with “ic”. The word “acid” is added to the end of the name. For example, aqueous HCl solution is named as hydrochloric acid. The strength of the binary acid is determined by how readily it donates H+ to the medium. If the bond between the hydrogen and the other element is weak, it can readily donate the proton; thus, the acid is stronger. The stability of the formed anion is also affecting the proton donation ability. For example, HI is a stronger acid than HCl, because I– anion is more stable than the Cl– anion.
These are acids, which contain an oxygen atom in the molecule. HNO3, H2SO4, H2CO3, H3PO4, CH3COOH are some of the common oxyacids. Other than the oxygen there is at least one another element, and at least one hydrogen atom in the molecule. The ability to donate one or more protons is essential to make the element an acid. The hydrogen of the oxyacid is bound with the oxygen atom. So in these acids the acidity is determined by the electronegativity of the central atom and the number of oxygen atoms.
What is the difference between Binary Acids and Oxyacids?
• Oxyacids contain at least one oxygen atom in the molecule and binary acids do not contain oxygen. Binary acids have hydrogen and another non metal element in the molecule.
• In oxyacids, the proton that is being donated is attached to the oxygen atoms. In binary acids, the hydrogens are attached to the other nonmetal element.
• The binary acid strength is determined by the bond strength of the H-X (X= nonmetal) bond. But in oxyacids, the acid strength is determined by the electronegativity of the central atom and the number of oxygen atoms.