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Question asked by Ranjeet R ,16 days back.Answered by Kirit Hathi, Tutor, MPT 34623 Q. Why does not Hydroxide ion concentration equal the concentration of Carbonic acid and bicarbonate ion in a Sodium Bicarbonate solution ? Ans. On dissolving NaHCO3 in water, molecules of NaHCO3 will ionize to give Na + ions and HCO3- ions. ( reaction 1 ). And molecules of Water, H2O, ionize giving H+ and OH- ions. ( reaction 2 ). Thus beaker will contain Na+ , HCO3- , H+ , and OH- ., and molecules of NaHCO3 which have not dissociated, not ionized.These ions will interact as given in reactions 3 and 4 below. Na+. Plus OH- will react to give NaOH molecules. This reaction is normally written in reverse when we want to talk about dissociation constant Ka and Kb. So writing conventionally, NAOH molecules ionize to give Na+ ions and OH- ions, a dissociation reaction involving Kb, dissociation constant for base, ( reaction 3 ). Thus, NaOH dissociates into Na+ ions and OH- ions, NaOH- Na + ions plus OH – ions.Similarly, writing the reaction 4 conventionally, we can say that H2CO3 dissociates giving H+ ions and HCO3 – ions. H2CO3  H+ ions plus HCO3 - ions Both these reactions go forward and simultaneously go backwards.Thus in reaction 3, as per forward reaction, NAOH dissociates giving Na+ ions and OH- ions. And as per reverse, backwards reaction, Na + ions combine with OH- ions giving NaOH molecules. Whether any reaction will largely go in forward direction or in reverse direction will depend upon its degree of dissociation as given by the value of Ka for acids and value of Kb for base, When the value of Ka is high, then forward ionization reaction is favored.And when value of Ka is low then reverse reaction is favored resulting in less ionization.Similarly for Kb. NAOH  Na + ions plus OH –ions. This is Forward reaction. Na + ions plus OH –ions will react to give NaOH molecules.A reverse,backward rection Writing conventionally in reaction 4, H2CO3 molecules will ionize giving H+ ions and. HCO3 – ions. H2CO3, Carbonic acid,is a weak acid having Ka = 4.5 x 10 -7. So, it will ionize very less ,giving less number of H+ ions and HCO3 – ions.Therefore, bicarbonate will be present mainly as Carbonic acid molecules, H2CO3 molecules, and not as HCO3- ions. In the beaker, H2CO3 molecules get formed due to the reaction between HCO3- ions coming from the ionization of NAHCO3 molecules and H+ ions coming from the dissociation of H2O into H+ ions and OH- ions. H+ plus HCO3- ions react to give H2CO3 molecules. In short, the beaker in which NaHCO3 is dissolved in water will be containing high concentration of OH – because NaOH is a strong base and dissociates completely giving OH- ions. Whereas Concentration of HCO3- ions will be less because H2CO3 is a weak acid and ionizes very less giving less concentration of HCO3- ions. Concentration of H2CO3 molecules will be high, but it is Not relevant because in ionic reactions, only ions take part in reactions and not molecules. . Question asked by Ranjeet R ,16 days back.Answered by Kirit Hathi, Tutor, MPT 34623 Q. Why does not Hydroxide ion concentration equal the concentration of Carbonic acid and bicarbonate ion in a Sodium Bicarbonate solution ? Ans. On dissolving NaHCO3 in water, molecules of NaHCO3 will ionize to give Na + ions and HCO3- ions. ( reaction 1 ). And molecules of Water, H2O, ionize giving H+ and OH- ions. ( reaction 2 ). Thus beaker will contain Na+ , HCO3- , H+ , and OH- ., and molecules of NaHCO3 which have not dissociated, not ionized.These ions will interact as given in reactions 3 and 4 below. Na+. Plus OH- will react to give NaOH molecules. This reaction is normally written in reverse when we want to talk about dissociation constant Ka and Kb. So writing conventionally, NAOH molecules ionize to give Na+ ions and OH- ions, a dissociation reaction involving Kb, dissociation constant for base, ( reaction 3 ). Thus, NaOH dissociates into Na+ ions and OH- ions, NaOH- Na + ions plus OH – ions.Similarly, writing the reaction 4 conventionally, we can say that H2CO3 dissociates giving H+ ions and HCO3 – ions. H2CO3  H+ ions plus HCO3 - ions Both these reactions go forward and simultaneously go backwards.Thus in reaction 3, as per forward reaction, NAOH dissociates giving Na+ ions and OH- ions. And as per reverse, backwards reaction, Na + ions combine with OH- ions giving NaOH molecules. Whether any reaction will largely go in forward direction or in reverse direction will depend upon its degree of dissociation as given by the value of Ka for acids and value of Kb for base, When the value of Ka is high, then forward ionization reaction is favored.And when value of Ka is low then reverse reaction is favored resulting in less ionization.Similarly for Kb. NAOH  Na + ions plus OH –ions. This is Forward reaction. Na + ions plus OH –ions will react to give NaOH molecules.A reverse,backward rection Writing conventionally in reaction 4, H2CO3 molecules will ionize giving H+ ions and. HCO3 – ions. H2CO3, Carbonic acid,is a weak acid having Ka = 4.5 x 10 -7. So, it will ionize very less ,giving less number of H+ ions and HCO3 – ions.Therefore, bicarbonate will be present mainly as Carbonic acid molecules, H2CO3 molecules, and not as HCO3- ions. In the beaker, H2CO3 molecules get formed due to the reaction between HCO3- ions coming from the ionization of NAHCO3 molecules and H+ ions coming from the dissociation of H2O into H+ ions and OH- ions. H+ plus HCO3- ions react to give H2CO3 molecules. In short, the beaker in which NaHCO3 is dissolved in water will be containing high concentration of OH – because NaOH is a strong base and dissociates completely giving OH- ions. Whereas Concentration of HCO3- ions will be less because H2CO3 is a weak acid and ionizes very less giving less concentration of HCO3- ions. Concentration of H2CO3 molecules will be high, but it is Not relevant because in ionic reactions, only ions take part in reactions and not molecules. .