Question

What is the colour of Nitric Acid?

• A. colourless
• B. Pure Nitric Acid (conc) is colourless and commercial Nitric Acid is yellowish brown.
• C. Yellowish Brown
• D. None of the above

Answer 1

The correct option is B

Pure Nitric Acid (conc) is colourless and commercial Nitric Acid is yellowish brown.

Pure Nitric acid (conc) is colourless.

Nitric acid, upon exposure to light and heat, will spontaneously decompose to nitrogen dioxide, water, and oxygen, creating the brownish-yellow color.It's not actually completely decomposing unless you leave it for a long time but there's enough dissolved nitrogen dioxide, which is what imparts the color, to give it a distinct yellowish brown color.