3 Si + 18 HF + 4 HNO3 → 3 H2SiF6 + 4 NO + 8 H2O
This is an oxidation-reduction (redox) reaction:
3 Si0 - 12 e- → 3 SiIV (oxidation)
4 NV + 12 e- → 4 NII (reduction)
Si is a reducing agent, HNO3 is an oxidizing agent.
Reactants:
- Si
- HF – Fluorane
- Other names: Hydrofluoric acid , Hydrogen fluoride , Fluorhydric acid
- Appearance: Colorless solution ; Colourless gas or colourless liquid (below 19.5 °C) ; Colourless gas or colourless fuming liquid with pungent odour ; Colourless fuming liquid with pungent odour ; Colorless gas or fuming liquid (below 67°F) with a strong, irritating odor. [Note: Shipped in cylinders.]
- HNO3 – Nitric acid
- Other names: Aqua fortis , Spirit of niter , Eau forte
- Appearance: Colorless, yellow or red fuming liquid ; Colourless-to-yellow liquid with pungent odour ; Colorless, yellow, or red, fuming liquid with an acrid, suffocating odor. [Note: Often used in an aqueous solution. Fuming nitric acid is concentrated nitric acid that contains dissolved nitrogen dioxide.]
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