Problem 62 - Chemistry The Molecular Nature of Matter

Question

Name these acids: (a) \(\mathrm{HF}(g),\) (b) \(\mathrm{HF}(a q)\)

Step-by-Step Solution

Answer

The name for (a) \(\mathrm{HF}(g)\) is hydrogen fluoride, and for (b) \(\mathrm{HF}(aq)\) is hydrofluoric acid.

Step 1: Identifying the State and Naming Gas

Firstly, identify the state of the compound. For (a) \(\mathrm{HF}(g)\), the state is given as gas (g). The naming of gaseous hydrogen fluoride doesn't follow the typical acid naming convention, because it's not dissolved in water. It is simply referred to by its molecular name, hydrogen fluoride.

Step 2: Naming the Aqueous Solution

For (b) \(\mathrm{HF}(aq)\), the state is given as aqueous (aq), which means it is dissolved in water and exists as an acid. Hydrogen fluoride in water is named hydrofluoric acid, according to the convention for naming binary acids, where the prefix 'hydro-' is added to the root name of the anion followed by 'ic acid'.

Key Concepts

Hydrogen Fluoride

Hydrogen fluoride, chemically represented as equation{HF}, is a compound consisting of hydrogen and fluorine. It is a colorless gas or liquid (depending on the conditions) that is highly corrosive and toxic. In its gaseous form, equation{HF(g)}, it is referred to by its molecular name, 'hydrogen fluoride,' rather than being named as an acid, since it is not in an aqueous state.

The properties of hydrogen fluoride are quite remarkable due to its high electronegativity and ability to form strong hydrogen bonds, which considerably influence its behavior and uses, often seen in industrial applications, including the production of refrigerants and herbicides, as well as in the glass etching and semiconductor industries.

Binary Acids

Binary acids are simple acids composed of two elements, hydrogen and one other nonmetal. The general formula for a binary acid is equation{HX}, where 'X' is the nonmetal anion. These are typically gases or liquids that, when dissolved in water, create an acidic solution.

These acids have unique naming rules. When naming a binary acid in its aqueous form, chemists include the prefix 'hydro-' to the anion’s root name, followed by the suffix '-ic' which is then followed by the word 'acid'. For instance, when hydrogen chloride gas equation{HCl(g)} is dissolved in water, it forms hydrochloric acid equation{HCl(aq)}. This naming convention is crucial for understanding chemical nomenclature and effectively communicating in the field of chemistry.

Acid Naming Convention

The acid naming convention is a set of rules used in chemistry to provide systematic names for acids. It is essential for conveying the correct chemical formula and understanding the properties of the substance. When naming acids that are binary (composed of hydrogen and one other element), the prefix 'hydro-' is added, and the suffix '-ic' is followed by 'acid'.

For example, the aqueous form of hydrogen fluoride is named 'hydrofluoric acid' to indicate it is a binary acid (hydrogen combined with fluorine) in solution. It is important not only to identify the composition of the molecule but also to consider its state, as it influences whether or not the substance is named as an acid. Therefore, understanding and applying the correct naming conventions is fundamental in chemistry education and practice.

Aqueous Solution State

The aqueous solution state, designated by the symbol equation{aq}, indicates that a substance is dissolved in water. Water’s role as a solvent is pivotal because it can dissolve a wide variety of substances, a property stemming from its polarity and ability to form hydrogen bonds. In chemistry, when a substance like hydrogen fluoride is in an aqueous solution, it undergoes dissociation to release ions.

For acids, this means that the release of equation{H^+} ions results in a solution with acidic properties, measurable by its pH level. Therefore, the behavior and naming of a substance can significantly change when it transitions from a gas or solid into an aqueous solution, influencing its reactivity and how it is named and classified.