Difference Between Hydrogen Fluoride and Hydrofluoric Acid

The key difference between hydrogen fluoride and hydrofluoric acid is that hydrogen fluoride is an inorganic compound whereas hydrofluoric acid is a solution of hydrogen fluoride in water.

Both hydrogen fluoride and hydrofluoric acid have the same chemical formula, HF, which contains a hydrogen atom and a fluorine atom. However, these are two different terms depending on the chemical and physical properties. Therefore, here, we will be discussing those differences between hydrogen fluoride and hydrofluoric acid.

1. Overview and Key Difference
2. What is Hydrogen Fluoride
3. What is Hydrofluoric Acid
4. Side by Side Comparison – Hydrogen Fluoride vs Hydrofluoric Acid in Tabular Form
5. Summary

What is Hydrogen Fluoride?

Hydrogen fluoride is a chemical compound having the chemical formula HF. It has a hydrogen atom and a fluorine atom bonded to each other via a covalent bond. It is a diatomic molecule, but in its solid form, there are zig-zag HF chains. These HF chains are created due to the strong hydrogen bonds that form between the HF molecules. The liquid form also contains this structure. Some chemical facts about this compound are as follows:

Molar mass is 20 g/mol
It occurs as a colourless gas; the liquid state is also colourless
The melting point is −83.6 °C while the boiling point is 19.5 °C
Due to the ability of HF to form hydrogen bonds, this compound is completely miscible with water

We can produce this compound by the reaction between sulfuric acid and pure grades of the mineral “fluorite”. However, most HF is produced as a byproduct of fertilizer production. There are several important uses of HF; as a precursor to organofluorine compounds, as a precursor for metal fluorides, as a catalyst, as a solvent, etc.

What is Hydrofluoric Acid?

Hydrofluoric acid is an aqueous solution of HF. That means it is a solution of hydrogen fluoride in water. We can write the chemical formula as HF_(aq). It appears as a colourless solution. Moreover, this solution is miscible with water. The IUPC name for this solution is Fluorane. The solution is a weak acid due to the strength of the H-F bond and the formation of clusters of HF, H₂O and F^–.

Furthermore, we can produce this weak acid by treating the mineral fluorite with sulfuric acid. There is a wide range of uses for hydrofluoric acid. The applications include the filed of oil refining, production of organofluorine compounds, production of fluorides, as a cleaning agent, etc.

What is the Difference Between Hydrogen Fluoride and Hydrofluoric Acid?

Comparing the properties of hydrogen fluoride and hydrofluoric acid, the key difference between hydrogen fluoride and hydrofluoric acid is that hydrogen fluoride is an inorganic compound whereas hydrofluoric acid is a solution of hydrogen fluoride in water. Therefore, hydrogen fluoride consists of H and F atoms, while hydrofluoric acid contains HF molecules in water.

The below infographic provides more details on the difference between hydrogen fluoride and hydrofluoric acid.

Summary – Hydrogen Fluoride vs Hydrofluoric Acid

In summary, hydrogen fluoride and hydrofluoric acid are two different forms of the same compound. Importantly, the key difference between hydrogen fluoride and hydrofluoric acid is that hydrogen fluoride is an inorganic compound whereas hydrofluoric acid is a solution of hydrogen fluoride in water.

Reference:

1. O’Neill, Tomás B., et al. “Complex Chemical Burns Following a Mass Casualty Chemical Plant Incident: How Optimal Planning and Organisation Can Make a Difference.” Burns, vol. 38, no. 5, 2012, pp. 713–718., doi:10.1016/j.burns.2011.12.010.

Image Courtesy:

1. “Hydrogen fluoride” By Original uploader was El T at en.wikipedia – Transferred from en.wikipedia (Public Domain) via Commons Wikimedia
2. “Hydrogen fluoride” By User:Dorgan – Self-photographed (CC BY-SA 3.0) via Commons Wikimedia