metalresearcher
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Acid and Base slags in non-aqueous environment ?
I sometimes read about acid slags (containing much SiO2) and basic slags on top of metal melts in metallurgical processes.
But are the terms 'acid' and 'base' not only for aqueous solutions as 'acid' contains H3O+ / H+ and 'base' OH- ?
And these ions are not present at all in metal slags.
What am I thinking wrong ?
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blogfast25
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Quote: Originally posted by metalresearcher  | I sometimes read about acid slags (containing much SiO2) and basic slags on top of metal melts in metallurgical processes.
But are the terms 'acid' and 'base' not only for aqueous solutions as 'acid' contains H3O+ / H+ and 'base' OH- ?
And these ions are not present at all in metal slags.
What am I thinking wrong ? |
The term acid and base in this context goes back a couple of centuries.
Oxides were once categorised as 'acid formers' or 'base formers' (to some extent that is still true but acid/base theory has evolved enormously since
then).
'Acid forming oxides' (in slags) are mainly Silica which (in theory) forms silicic acid (simplest form H2SiO3) which forms
silicates. Slag silica can be 'neutralised' by strong bases like lime (or limestone).
'Base forming oxides' by contrast would be CaO, Na2O, K2O, alumina (an amphoteric oxide) etc.
Silica is mostly the result of residual gangue material accompanying the target ore (e.g. iron ore).
[Edited on 3-9-2016 by blogfast25]
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DraconicAcid
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There are several definitions of acids and bases, the most common being the Bronsted-Lowry definition (acids give up H+, bases accept H+). There's
also the not-maligned-enough Arrhenius definition (acids contain H+, bases contain OH-, so that ammonia and carbonate aren't really bases, but "base
analogues", so nobody ever uses that one except in high school textbooks), the Lux-Flood definition (acids accept oxide ions, bases contribute oxide
ion, which is useful for slags and melts), and the Lewis definition (an acid accepts an electron pair, and a base contribute an electron pair).
So a reaction like Na2O + SiO2 -> Na2SiO3 is an acid-base reaction according to the Lewis and Lux-Flood definitions. Same with CaO + SO3 ->
CaSO4
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Texium
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Thread Moved
27-11-2023 at 10:50 |
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