What characterizes a substance as an acid?
An acid is any species that increases concentrations of the characteristic cation of the solvent.
What does the above spray mean?
Well, water undergoes an equilibrium reaction, that has been extensively measured:
Now, clearly, this is an equilibrium reaction, and at
Typical acids are the so-called mineral acids,
Now water is a very important solvent system, yet it is not the only solvent system. I could perform my reactions in say acetic acid or hydrogen fluoride, if I wanted a more acidic solvent than water; or could perform my reactions in liquid ammonia, if I wanted a more basic solvent system.
In liquid ammonia, (which is much harder to study than the water-based solvent system), we conceive the acid/base equilibrium reaction as:
Here, our definition of an acid is the same as previous, but we have moved to a different solvent. The characteristic cation of the ammonia solvent is ammonium ion, whereas the characteristic anion is
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