Chemistry Forum

Regarding wet washing:
What are the functions of the three digestion reagents: HCl, HNO₃ and HClO₄?
And why is HClO₄ not introduced until the second heating?
Why is fresh HNO₃ and HClO₄ added?. Why has HNO₃ to be present when the reagent is treated with HClO₄ treatment?
Thank you very much!

Nitric acid and perchloric acid are strong oxidizers who oxidise everything to Oxides or nitrates. Hydrochloric acid change the oxides to chloride, which have good solubility in water.
The order is because Perchlorate and nitrogen compounds like ammonium are explosive, so first these compounds have to convert by nitric and others like some metals later will be treated with perchlorate.

Can we replace them by any reagents that's cheaper than them?