Abstract
Carbonic acid, traditionally classified as inorganic, presents the highest oxidation state of carbon in an redox hierarchy of organic compounds. The paper deals with common mistake of publishing wrong value of 1st dissociation constant of carbonic acid as pK1 = 6,84, which in fact is the "observed" dissociation constant, instead of the correct value of pK1 = 3,84.
The paper also presents the way of suggesting the strength of an oxoacid from its molecular formula. Presented concept can be used as an aid for pupils in lower secondary schools who are unable to do computations involving logarithms and equilibrium constants yet.
The concept is based on the difference between number of oxygen and hydrogen atoms in the formula. Correlation between this difference and the number of mesomeric structures for corresponding acid anion and thus the stability of such anion is quite straightforward.