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Conjugate Pairs. The strength of an acid (or base) is determined by the amount of IONIZATION . HNO 3 , HCl, H 2 SO 4 and HClO 4 are among the only known strong acids. Strong vs. Weak Acids. Strong acid is one that ionizes completely
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The strength of an acid (or base) is determined by the amount of IONIZATION. HNO3, HCl, H2SO4 and HClO4 are among the only known strong acids.
Strong vs. Weak Acids • Strong acid is one that ionizes completely • HNO3 (aq) ---> H+ (aq) + NO3- (aq)
Weak Acids • Weak acids are much less than 100% ionized in water. • One of the best known is acetic acid = CH3CO2H
Base Strength • Any substance that ionizes completely to form OH- ions are strong bases • These solutions are said to be alkaline • NaOH, Ca(OH)2
Acid/Base Reactions • Whenever an acid and base react, two conjugates are produced • Conjugate base – the species that remains after the acid has given up its proton • Conjugate acid – the species that remains after the base has accepted the proton
Equilibrium • Acid/Base reactions are not just forward, the reverse reaction is also always occurring • The reaction always favors the production of the weaker acid and weaker base • The stronger the two initial reactants, the more violent the reaction
Example • For the reaction shown below, HC2H3O2 + H2O C2H3O2- + H3O+ a) Identify the acid, base, conjugate acid, and conjugate base. b) Determine which direction (forward or reverse) is favored.