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That CAN'T be true! / do acids reduce metals?
« on: 28/09/2016 01:30:23 »Fluoroantimonic acid has the chemical formula HSbF6, and a molar mass of 236.76 g/mol. It is a very strong acid, in that it is capable of protonating almost anything, but that doesn't necessarily mean that it is the best at dissolving (eating through) materials.
I don't think that metals like steel are soluble in HSbF6, and protonating steel won't change its solubility, so really the question at hand is one about the chemical reactions:
HSbF6 --> H+ + SbF6–
and
Fe + 2 H+ --> Fe++ + H2
These reactions indicate the dissociation of the acid into free protons (hydronium ions) and hexafluoroantimonate ions, and the reaction of protons with metallic iron (steel), resulting in soluble ferrous ions and hydrogen gas.
Based on this stoichiometry, it would take 2 moles of acid to react with one mole of iron (molar mass of 56 g/mol). One kg of the acid contains just over 4 moles (1000/236.76 = 4.22 moles), so this would eat away 2.11 moles of iron, or roughly 120 grams.
In contrast, one kg of sulfuric acid, which is H2SO4, could consume roughly 560 grams of iron. Sulfuric acid is no where near as "strong" based on dissociation constant, but it has a much higher concentration of reactive protons per unit mass.
i hope this helps!
If you heat most acids they become more potent, sulfuric is one of them. It can reduce many metals like aluminum in seconds or minutes once it is hot. But it does not effect steel 55 gallon drums very much even when hot.
Sincerely,
William McCormick