Final answer:
The order from greatest to least concentration in a 1.0x10⁻⁴ M solution of HClO is: water (H₂O), hydronium ion (H₃O⁺), hypochlorous acid (HClO), hypochlorite ion (OCl⁻), and hydroxide ion (OH⁻), (H₂O > H₃O⁺ > HClO > OCl⁻ > OH⁻).
Step-by-step explanation:
Arranging a 1.0x10⁻⁴ M solution of HClO by ion concentrations from greatest to least, we would expect H₂O to have the highest concentration since it is the solvent. H₃O⁺ would be next, as HClO is a weak acid and partially dissociates into H₃O⁺ and OCl⁻ ions.
However, due to the autoionization of water, there will also be a very small but equal concentration of OH⁻ present. Since the solution is acidic, the concentration of H₃O⁺ will be greater than that of OH⁻.
Knowing that the concentration of the acid, HClO, is 1.0x10⁻⁴ M, and some of it has dissociated, the concentration of undissociated HClO will be slightly less than 1.0x10⁻⁴ M but greater than the concentration of its conjugate base, OCl⁻.
Lastly, the concentration of OCl⁻, the conjugate base formed from the dissociation of HClO, will be the least after HClO. Therefore, the order from greatest to least concentration is H₂O > H₃O⁺ > HClO > OCl⁻ > OH⁻.