Acid–base reaction

"Perhaps the most important of all concepts related to electronegativity and polarity is that of acidity and basicity. We’ll soon see, in fact, that the acid–base behavior of organic molecules explains much of their chemistry."

"Acids differ in their ability to donate H+. Stronger acids, such as HCl, react almost completely with water, whereas weaker acids, such as acetic acid (CH3CO2H), react only slightly. The exact strength of a given acid HA in water solution is described using the acidity constant (Ka) for the acid dissociation equilibrium."