Question

Write the formula for each acid. a. phosphoric acid b. hydrocyanic acid c. chlorous acid

Short answer

a. Phosphoric acid: H3PO4, b. Hydrocyanic acid: HCN, c. Chlorous acid: HClO2.

Step-by-step solution

Determining the Formula of Phosphoric Acid

To write the formula for phosphoric acid, you must know it is a ternary acid (containing hydrogen, oxygen, and another element). The other element here is phosphorus. Phosphoric acid has the chemical name 'H3PO4'. Therefore, its formula is H3PO4.

Determining the Formula of Hydrocyanic Acid

Hydrocyanic acid is a binary acid (containing hydrogen and one other non-metal element). The other element in this case is cyanide (CN). Hydrocyanic acid has the chemical formula 'HCN'.

Determining the Formula of Chlorous Acid

Chlorous acid is a ternary acid with chlorine in a +3 oxidation state. Oxygen is also part of its composition. The formula for chlorous acid is HClO2.

Key concepts

Phosphoric Acid Formula

Understanding the formula for phosphoric acid is crucial when diving into the study of chemistry, as it's a common acid used in various applications, from fertilizers to soft drinks. Structurally, phosphoric acid is represented as \( H_3PO_4 \). It falls into the category of ternary acids, which means it consists of hydrogen, oxygen, and another element, which in this case is phosphorus. The subscript '3' tells us that there are three hydrogen atoms, while the 'PO_4' indicates that one phosphorus atom is bonded to four oxygen atoms. This composition is fundamental to recognizing how phosphoric acid behaves in chemical reactions.

Remember, when writing chemical formulas, it's necessary to balance the charges between the atoms involved. Phosphorus, typically found in a +5 oxidation state when bonded to oxygen in acids, aligns with the negative charges of the four oxygen atoms, resulting in a neutral compound overall.

Hydrocyanic Acid Formula

Hydrocyanic acid is somewhat of an exception in the world of acids because it's quite simple but notoriously potent. Its formula, \( HCN \), denotes a binary acid. These acids are defined by their composition of just hydrogen and one other non-metal element—in this case, cyanide (CN).\

\This acid is an important organic synthesis material and used in creating a variety of chemical products. When writing its formula, keep in mind that the hydrogen (H) is bonded to the cyanide group, which is composed of a carbon (C) and a nitrogen (N) atom. The simplicity of the hydrocyanic acid formula is misleading, as the compound itself is highly toxic and requires careful handling.

Chlorous Acid Formula

Chlorous acid, which has the formula \( HClO_2 \), is representative of ternary acids that comprise of hydrogen, oxygen, and one other element—chlorine, in this case. What makes chlorous acid stand out is the specific oxidation state of chlorine here; +3.\

\It is a less commonly encountered acid but still relevant in chemical studies. The '2' after oxygen in the formula indicates that there are two oxygen atoms. The presence of only one hydrogen atom in chlorous acid's formula means it can provide one proton (\( H^+ \) ion) in an aqueous solution, classifying it as a monoprotic acid. Being able to write and understand such formulas is essential for exploring the behaviors and reactions of different acids in chemistry.

Binary and Ternary Acids

The world of acids can be categorized based on the number and types of elements they contain, leading us to the concepts of binary and ternary acids. Binary acids consist of only two different elements: hydrogen and a non-metal. Common examples include hydrochloric acid (\( HCl \)), where chlorine is the non-metal, and hydrofluoric acid (\( HF \)), where fluorine plays that role.

On the other hand, ternary acids, also known as oxyacids, contain three elements: hydrogen, oxygen, and another non-metal or metalloid element. Phosphoric acid (\( H_3PO_4 \)) and chlorous acid (\( HClO_2 \)) are typical examples.\

\To recognize and write the formulas of these acids correctly, identifying the constituent elements and their respective counts is necessary. Binary acids are recognized by their 'hydro-' prefix and '-ic' suffix with their non-metal names, while ternary acids often have names ending in '-ous' or '-ic,' depending on the oxidation state of the central non-metal element.