17 Water 2a

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Unformatted text preview: ;- > H+(aq) + HCO3- (aq) (bicarbonate ion) •  HCO3- (aq) <- > H+(aq) + CO3 2- (aq) (carbonate ion) Andrews et a., 2004 (Remember for our purposes a and [ ] are interchangeable terms) Remember: pH = - (log [H+]) Carbonic acid chemistry and pH H . . ALKALINITY •  Pure H2O and CO2: •  H2O, H+ , OH- , H2CO3 ,HCO3- ,CO32- •  When pH < 7 [CO32- ],[OH- ] negligible •  H+ , OH- , H2CO3 ,HCO3- ,CO32- •  Therefore [H+] ≅ [HCO3- ] (if all HCO3- arises from dissociaEon of H2CO3 ) •  Want to measure how much HCO3- is not associated with H+ in origin i.e. Natural waters – other sources of HCO3- / CO32- •  Ex. calcite •  CaCO3 ⇔ Ca 2+ + CO3 2- •  In terms of charge balances, adding calcite to water would give: •  2[Ca 2+ ] + [H+] ⇔ [HCO3- ] + 2 [CO32- ] + [OH- •  AddiEon of acid would change [ ]’s of all but [Ca 2+ ] •  [Ca 2+ ] : conservaEve •  remainder: non- conservaEve •  Therefore, grouping conservaEve and non- conservaEve (moles/l): •  2[Ca 2+ ] = [HCO3- ] + 2 [CO32- ] + [OH- - [H+] •  Th...
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This note was uploaded on 01/30/2014 for the course ESCI 271 taught by Professor Lisakellman during the Fall '12 term at St. Francis Xavier, Antigonish.

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