Question

Which of the following statements about polyprotic acids is incorrect?

a. polyprotic acids can furnish 2 or more hydronium ions per molecule
is generally accepted practice to ignore second or third ionizations when caluclating the concentration of H3O+
c. the ionizations of polyprotic acids occur simulataneously
d. successice ionization constants for polyprotic acids generally decrease
e. phosphoric acid is a typocal polyprotic acid

Answer 1

The incorrect statement about polyprotic acids is that their ionizations occur simultaneously; they actually ionize in a stepwise manner with each step having a lower ionization constant than the previous one.

Step-by-step explanation:

The statement about polyprotic acids that is incorrect is: 'the ionizations of polyprotic acids occur simultaneously'. In fact, polyprotic acids like H2SO4, H3PO4, and H2CO3 release their protons in a stepwise manner. The first dissociation is generally the strongest and subsequent ionizations release protons with decreasing acid strength. For calculating the concentration of H3O+ ions, it is usually sufficient to consider only the first ionization, especially when the difference in the ionization constants between steps is significant, often by a factor of about 105 to 106.