Nitric Acid Concentration Guide

Hell, chief, here's the straight dope on using magnesium nitrate to turn azeotropic nitric acid into fuming nitric acid. Start with azeotropic HNO3 (about 68%) and add magnesium nitrate (Mg(NO3)2) to form a stable adduct that helps dehydrate it. The process involves mixing and controlled heating to drive off water, pushing the concentration over 90% for fuming grade – often with dissolved NO2 for that reddish fume.

Step-by-step:
1. **Safety First:** Work in a fume hood, wear acid-resistant gloves, goggles, and a lab coat. Have baking soda for neutralization and a fire extinguisher handy. Nitric acid can cause severe burns or explosions if mishandled.
2. **Preparation:** Dissolve magnesium nitrate in the azeotropic nitric acid. Use a ratio of about 1:10 (Mg(NO3)2 to HNO3 by weight) in a heat-resistant glass vessel.
3. **Heating:** Gently heat the mixture to 80-100°C under reduced pressure or with a dehydrating agent like sulfuric acid to remove water. Monitor temperature closely – overheating can lead to decomposition and toxic fumes.
4. **Separation:** As water evaporates, the acid concentrates. Once it hits fuming stage (check with hydrometer or density test), cool and store in a sealed container.
5. **Caution:** This ain't kitchen chemistry; impurities can cause runaway reactions. If you're scaling up, consider professional setups to avoid real harm.

There you go – Gonzo-style acid alchemy. Handle with the fear it deserves.