Acid-base Dissociation • For any acid, describe it’s reaction in water: – H x A + H 2 O x H + + A - + H 2 O – Describe this as an equilibrium expression, K (often denotes K A or K B for acids or bases…) • Strength of an acid or base is then related to the dissociation constant Big K, strong acid/base! • pK = -log K as before, lower pK=stronger acid/base! ] [ ] ][ [ A H H A K x x
Acid-base Dissociation. For any acid, describe it’s reaction in water: H x A + H 2 O x H + + A - + H 2 O Describe this as an equilibrium expression, K (often denotes K A or K B for acids or bases…) - PowerPoint PPT Presentation
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Acid-base Dissociation• For any acid, describe it’s reaction in water:
– HxA + H2O x H+ + A- + H2O
– Describe this as an equilibrium expression, K (often denotes KA or KB for acids or bases…)
• Strength of an acid or base is then related to the dissociation constant Big K, strong acid/base!
• pK = -log K as before, lower pK=stronger acid/base!
][
]][[
AH
HAK
x
x
pKx?
• Why were there more than one pK for those acids and bases??
• H3PO4 H+ + H2PO4- pK1
• H2PO4- H+ + HPO4
2- pK2
• HPO41- H+ + PO4
3- pK3
• LOTS of reactions are acid-base rxns in the environment!!
• HUGE effect on solubility due to this, most other processes