Rank the solutions in order of decreasing [H3O+]. Rank solutions from largest to smallest hydronium ion concentration. To rank items as equivalent, overlap them. ResetHelp 0.10 M HC2H3O20.10~ M~ H C Subscript2 H Subscript3 O Subscript2 0.10 M HF0.10~ M~ H F 0.10 M HBr0.10~ M~ H B r 0.10 M HC6H5O0.10~ M~ H C Subscript6 H Subscript5 O

Rank the solutions in order of decreasing [H₃O⁺]. Rank solutions from largest to smallest hydronium ion concentration. To rank items as equivalent, overlap them.

HC₂H₃O₂ 0.10 M (acetic acid)
HF 0.10 M
HBr 0.10 M
HC₆H₅O 0.10 M (phenol)

For weak acids, the concentration of H₃O⁺ can be calculated using the following expression:

[H₃O⁺] = √(Ka × Ca)

where,

Ka is the acid dissociation constant

Ca is the initial concetration of the acid

For monoprotic strong acids, the concentration of H₃O⁺ is:

[H₃O⁺] = Ca

HC₂H₃O₂ 0.10 M (acetic acid)

Acetic acid is a weak acid that ionizes according to the following equaion:

HC₂H₃O₂(aq) + H₂O(l) ⇄ C₂H₃O₂(aq)⁻ + H₃O⁺(aq)

[H₃O⁺] = √(Ka × Ca) = √(1.8 × 10⁻⁵ × 0.10) = 1.3 × 10⁻³ M

HF 0.10 M

HF is a weak acid that ionizes according to the following equation:

HF(aq) + H₂O(l) ⇄ F⁻(aq) + H₃O⁺(aq)

[H₃O⁺] = √(Ka × Ca) = √(6.6 × 10⁻⁴ × 0.10) = 8.1 × 10⁻³ M

HBr 0.10 M

HBr is a strong acid that ionizes according to the following equation:

HBr(aq) + H₂O(l) ⇒ Br⁻(aq) + H₃O⁺(aq)

[H₃O⁺] = Ca = 0.10 M

HC₆H₅O 0.10 M (phenol)

Phenol is a weak acid that ionizes according to the following equation:

HC₆H₅O(aq) + H₂O(l) ⇄ C₆H₅O(aq)⁻(aq) + H₃O⁺(aq)

[H₃O⁺] = √(Ka × Ca) = √(1.3 × 10⁻¹⁰ × 0.10) = 3.6 × 10⁻⁶ M