Acidic hydrogen atoms are those which will be transferred to what?
another atom
water
a cup
a base
Acids can further be categorized based on how many acidic hydrogen atoms they contain. Acidic hydrogen atoms are those which will be transferred to a base. A monoprotic acid has only one acidic hydrogen that would be transferred to a strong base, whereas a polyprotic acid has two or more. Common monoprotic acids include HCl, HBr, and HNO 3 . A common diprotic acid is sulfuric acid (H 2 SO 4 ), and phosphoric acid (H 3 PO 4 ) provides an example of a triprotic acid. In each case, all hydrogens are available to participate in acid-base reactions. However, that is not the case for all acidic molecules. For example, in acetic acid (CH 3 COOH), only the hydrogen bonded to the oxygen atom is acidic. The other three hydrogens are covalently bonded to carbon and cannot be removed by any of the bases that we will consider in this chapter.