Unformatted text preview: nit ion, an acid is a proton donor, and a base is a proton acceptor. +
HCl (g) + H2O (l) → H3O (aq) + Cl (aq) (acid) (base) –
NH3 (aq) + H2O (l) → NH4+ (aq) + OH (aq) (base) (acid) · A substance that can act as a BrønstedLowry acid and base (such as water) is called amphiprotic.
· In BrønstedLowry definit ion, any pair of mo lecules or ions that can be interconverted by transfer of a proton is called conjugate acidbase pair. –
HCl (g) + H2O (l) → Cl (aq) + H3O (aq) (acid) (base) (conjugate base (conjugate acid of HCl) of H2O) –
NH3 (aq) + H2O (l) → NH4+ (aq) + OH (aq) (base) (acid) (conjugate acid (conjugate base of NH3) of H2O) 2 Chemistry 51 Chapter 10 BRØNSTEDLOWRY ACIDS & BASES Examples: 1. Ident ify the conjugate acidbase pairs for each reaction shown below: –
H2O + Cl –
® HCl + OH –
C6H5OH + C2H5O ® C6H5O + C2H5OH 2. Write the formula for the conjugate acid for each base shown: –
HS NH3 CO32– 3. Write the formula for the conjugate base for each acid shown: HI CH3OH HNO3 3 Chemistry 51 Chapter 10 ACID & BASE STRENGTH
· According to the Arrhenius definit io n, the strength of acids and bases is based on the amount of their ionization in water.
· Strong acids and bases are those that ionize completely in water.
· Strong acids and bases are strong electrolytes. –
HCl (aq) ¾¾ H (aq) + Cl (aq) ®+ –
NaOH (s) ¾H2 O¾ Na+ (aq) + OH (aq)
¾® · Weak acids and bases are those that ionize partially in water, and are therefore written as ¾¾
reversible reactions (indicated by ¬¾ ).
· Weak acids and bases are weak electrolytes. ¾H 2 O¾
HC 2 H 3O 2 ¬¾ ¾ H + (aq) + C 2 H 3O 2 (aq) ¾¾
NH 3 (aq) + H 2 O (l) ¬¾ NH + (aq) + OH (aq) ¾
4 Ionization of Strong vs. Weak acids 4 Chemistry 51 Chapter 10 ACID & BASE STRENGTH
· Listed below are the formulas and names of co mmon acids and bases, and...
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