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

Problem 15.46

Which has the lower pH, 0.00048 M H2SO4 or a vinegar solution having pH = 2.42?


The first hydrogen atom in sulfuric acid is 100% ionized but the second is not. However, if the second hydrogen atom also were 100% ionized, then [H3O+] = 2×0.00048 = 0.00096 M giving a pH = –log[H3O+] = –log[0.00096] = 3.02. Thus, the pH for the sulfuric acid solution must be greater than 3.02 so the vinegar solution has the lower pH.