Definition according to Arrhenius
The first scientifically closed acid-base theory was developed by the Swedish chemist Svante Arrhenius. In his 1887 definition - do my assignment , he still understood an acid to be a substance that tastes sour, but also a substance that forms hydrogen ions or protons (=H+) in aqueous solution.
In water, an acid thus dissociates into hydrogen ions and acid residue ions according to the following general equation:
HA -→ H+ + A- In this case, HA generally stands for an ARRHENIUS acid and A- is the acid residue ion formed during dissociation.
For nitric acid, the equation is:
HNO3 -→ H+ + NO3-. Nitric acid dissociates in water into hydrogen ions and nitrate ions = acid residue ions.
According to ARRHENIUS, a base is a substance that tastes soapy or alkaline and forms hydroxide ions in water.
In general, the following applies to metal hydroxides
MOH -→ M+ + OH-. Example sodium hydroxide:
NaOH -→ Na++ OH- This definition had to be extended, however, because it had a decisive disadvantage. ARRHENIUS limited his definition only to aqueous solutions - take my online class for me . Water was therefore always necessary for the formation of an acid or base. However, acid-base reactions that did not take place in aqueous solutions were already known.
It was also recognised that bases such as ammonia do not necessarily have to contain hydroxide ions and that free protons - chemistry solver (hydrogen ions) cannot exist in aqueous solutions.