Fascinating Differences Between Fuming Nitric Acid and Concentrated Nitric Acid

What are the main differences between fuming nitric acid and concentrated nitric acid?

How does the composition and reactivity of fuming nitric acid and concentrated nitric acid differ?

Main Differences Between Fuming Nitric Acid and Concentrated Nitric Acid

The main differences between fuming nitric acid and concentrated nitric acid lie in their composition and reactivity.

Fuming nitric acid, also known as red fuming nitric acid (RFNA), is a more concentrated form of nitric acid that contains dissolved nitrogen dioxide. This dissolved nitrogen dioxide gives fuming nitric acid a reddish-brown color and increases its reactivity. As a result, fuming nitric acid is a powerful oxidizer, often used in rocket propellants due to its high concentration and strong oxidizing properties.

On the other hand, concentrated nitric acid is typically around 68%-70% nitric acid in water and is colorless or yellowish in appearance due to the presence of nitrogen oxides. While concentrated nitric acid is also a strong oxidizer, it is less concentrated and less reactive compared to fuming nitric acid. Concentrated nitric acid is commonly used in laboratory settings for various chemical reactions.

In terms of mechanisms, the presence of nitrogen dioxide in fuming nitric acid allows it to readily participate in nitrations, where a nitro group is added to an organic molecule. Concentrated nitric acid can also perform similar reactions, but often requires the assistance of other chemicals or higher temperatures to do so efficiently.