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J. W. Hill, R. H. Petrucci, T. W. McCreary, & S. S. Perry General Chemistry 4th edition

Review Question 15.1

Write equations to represent the ionization of HI as an acid in both the Arrhenius and Brønsted-Lowry theories.


HI is a strong acid, so will ionize completely.

In Arrhenius theory, the acid dissociates into a hydrogen ion and the anion. For HI, then:

HI(aq) H+(aq) + I(aq)

In Brønsted-Lowry theory, the acid is a hydrogen ion donor and another species is required to act as the hydrogen ion acceptor. In aqueous solution, the hydrogen ion acceptor is water, so:

HI(aq) + H2O(l) H3O+(aq) + I(aq)