H.O+is the strongest acid that can exist in aqueous solution. 1)Acids stronger than H3O+react with H2O(amphiprotic substance)to produce hydronium H3O+and their conjugate bases.e.g., HA+H20→A+H30+ acid(2)base(1)base(2)acid(1) where "HA"is generically a strong acid such as HCIO4> HCI,HNO3. HCI(aq)+H2O-H3O+(aq)+CI(aq) acid(2)base(1)base(2)acid(1) H2O can not differentiate strong acids (levelling effect)
H3O+ is the strongest acid that can exist in aqueous solution. HCl(aq) + H2O →H3O+ (aq) + Cl- (aq) H2O can not differentiate strong acids (levelling effect) HA + H2O → A- + H3O+ where “HA” is generically a strong acid such as HClO4， HCl，HNO3 . 1)Acids stronger than H3O+ react with H2O(amphiprotic substance) to produce hydronium H3O+ and their conjugate bases. e.g., acid(2) base(1) base(2) acid(1) acid(2) base(1) base(2) acid(1)
2)Acids weaker than H3O+react with H2O to a much smaller extent,producing H3O+and their conjugate bases (differentiating effect).e.g., HF(aq)+H2O=H3O(aq)+F(aq) acid(2)base(1)base(2)acid(1) 3)How to differentiate their acidity of strong acids? a less basic(弱碱性)solvent(versus water)can differentiate the relative acidic strength of the acids,e.g., HAC,where the strong acids do not ionize completely. HCI(aq)+HAc-HAc(aq)+Cl(aq) acid(2)base(1) base(2) acid(1) Order of the strength of the following acids: HI>HCIO>HCI>H2SO>HNO
a less basic(弱碱性) solvent (versus water) can differentiate the relative acidic strength of the acids, e.g., HAC, where the strong acids do not ionize completely. HI＞HClO4＞HCl＞H2SO4＞HNO3 2)Acids weaker than H3O+ react with H2O to a much smaller extent, producing H3O+ and their conjugate bases (differentiating effect). e.g., HF(aq) + H2O → H3O+ (aq) + F- (aq) Order of the strength of the following acids： 3) How to differentiate their acidity of strong acids? acid(2) base(1) base(2) acid(1) HCl(aq) + HAc →H2Ac+ (aq) + Cl- (aq) acid(2) base(1) base(2) acid(1)
OH is the strongest base that can exist in aqueous solution 1)Bases like O2-.H,NH2,CH3,which are stronger than OH,react with H2O to produce OH and their conjugate acids (levelling effect).e.g., O2-(aq)+H2O-OH(aq)+OH(aq) base(1)acid(2) acid(1) base(2) H2O can not differentiate strong bases. 2)Bases weaker than OH-react with H2O to a much smaller extent,producing OH-and their conjugate acisds (differentiating effect).e.g., H2O (aq)+NH3(aq)-OH(aq)+NH(aq) acid(2) base(1) base(2) acid(1)
OHis the strongest base that can exist in aqueous solution O2- (aq) + H2O → OH- (aq) + OH- (aq) H2O can not differentiate strong bases. 1) Bases like O2-、H- , NH2 - , CH3 - , which are stronger than OH- , react with H2O to produce OH- and their conjugate acids (levelling effect). e.g., 2) Bases weaker than OH- react with H2O to a much smaller extent, producing OH- and their conjugate acisds (differentiating effect). e.g., H2O (aq) + NH3 (aq) →OH- (aq) + NH4 + (aq) acid(2) base(1) base(2) acid(1) base(1) acid(2) acid(1) base(2)
3)How to differentiate their strength of strong bases? A solvent(弱酸性)whose strength of acid is a weaker than that of H2O can do it (differentiating effect),e.g.,NH3 O2+NH3 =OH +NH2 base(1) acid(2) acid(1) base(2)
3) How to differentiate their strength of strong bases? A solvent （弱酸性） whose strength of acid is a weaker than that of H2O can do it (differentiating effect), e.g., NH3 O2- + NH3 = OH- + NH2 - base(1) acid(2) acid(1) base(2)
For a conjugate acid-base pair: The stronger the acid,the weaker its conjugate base; The stronger the base,the weaker its conjugate acid. Strength of acid酸性：HClO4>H,SO4>H3PO4> HAc>H2 CO3>NH>H,O Strength of base碱性：ClO4<HSO:<H,PO,< Ac<HCO<NH <OH concepts 酸浓度(concentration of acid):以溶质酸的量计算得到的 浓度(mol.H);酸度(acidity):溶液中H+离子浓度或pH值； 酸强度((strength of acid)：酸的强弱K或pK
The stronger the acid，the weaker its conjugate base； The stronger the base，the weaker its conjugate acid. HAc H CO NH H O HClO H SO H PO 2 3 4 2 4 2 4 3 4 + 酸性： - - - - - - Ac HCO NH OH ClO HSO H PO 3 3 碱性： 4 4 2 4 Strength of acid Strength of base For a conjugate acid-base pair: 酸浓度(concentration of acid):以溶质酸的量计算得到的 浓度(mol.l-1 ); 酸度(acidity)：溶液中H +离子浓度或pH值; 酸强度(strength of acid )：酸的强弱 θ a θ Ka 或pK concepts