HIST/CHEM - ACIDS AND BASES EQUILIBRIUM ACID STRENGTH The...

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ACIDS AND BASES EQUILIBRIUM ACID STRENGTH The strength of an acid is determined by its degree of ionization. A strong acid completely ionizes and a weak acid ionizes slightly. In an aqueous solution, the ionization reaction of a weak acid, HA, is represented by the following equation: The equilibrium constant for this reaction is Ka = A stronger acid has a --------------- Ka. A weaker acid has a ---------------- Ka. A strong acid completely ionizes in water and therefore, its Ka ……………………… The conjugate base of a strong acid is very weak to the point where it is not interested in accepting a proton! Therefore, the ionization of a strong acid in water is not reversible. The conjugate base of a weak acid is not very weak and easily accepts a proton. Therefore, the ionization of a weak acid in water is reversible. The conjugate base of the acid HA is A - . A stronger acid has a -------- conjugate base. QUESTION: Compare the strength of the conjugate bases of HF, HCl and HBr. Which of the conjugate bases can accept a proton from water? QUESTION: Compare the strength of the conjugate bases of acetic acid (Ka = 1.8 x 10 -5 ) to that of nitrous acid (Ka = 4.0 x 10 -4 ). AUTOIONIZATION OF WATER A substance that can behave both as an acid and as a base is called: AMPHOTERIC (AMPHIPROTIC when the solvent is water). Water is an amphoteric substance. This is illustrated by its autoionization: H 2 O (l) + H 2 O (l) H 3 O + (aq) + OH - (aq) 1
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The equilibrium constant for this reaction is called the water ionization constant or the ion-product constant and is represented by: Kw = ………………………. . In a neutral solution, [H
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HIST/CHEM - ACIDS AND BASES EQUILIBRIUM ACID STRENGTH The...

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