PART 5-Acids and bases Reference: Chapter 15, 16.1-16 4 in textbook
PART 5 – Acids and Bases Reference: Cha p , ter 15, 16.1 —16.4 in textbook 1
Bronsted-LoWey Definition Acid Compound that can increase the hydrogen ion(Ht) concentration when dissolved in water e.g. HCI(ag)+ H2O()H3O+(ag)+ Cl(aq) e.g. HCN(aq)+ H20 ()>H3O+(aq)+ CN(aq) Base Compound that can increase the hydroxide ion(OH-) concentration when dissolved in water g NaoH(aq)> Na(ag)+ OH (ag) e.g. NH3(aq)+ H2o()NH4(aq)+ OH(aq)
Brønsted-Lowe y Definition z Acid Compound that can increase the hydrogen ion (H +) concentration when dissolved in water concentration when dissolved in water. ¾ e.g. HCl (aq) + H 2O (l) Æ H 3 O + (aq) + Cl- (aq), ¾ e g HCN (aq) + H2O (l) Æ H O + (aq) + CN- ¾ e.g. HCN (aq ) + H2O (l) Æ H (aq ) 3 O (aq ) + CN (aq ) z Base Compound that can increase the hydroxide ion (OH-) concentration when dissolved in water. ¾ e.g. NaOH (aq) Æ Na + (aq) + OH-(aq) ¾ e.g. NH 3 (aq) + H 2O (l) Æ NH 4 + (aq) + OH- (aq) 2
Strong and Weak Acid(Base) Strong acid(base) Strong acid completely dissociated into h+& anions in water (e.g.HC,HN○3,H2SO4,HBr,H,HC|O4…) Strong base: completely dissociated into OH& cations in water (all IA, IIA cations hydroxide, e.g. NaOH, Ba(OH)2,.) Weak acid(base) Weak acid: partially dissociated, majority as molecules e.g. HF, HCIO, HCN, H2s, HCOoH (formic acid), CH3COOH (acetic acid), HCO3, H2o, Weak base: partially dissociated, majority as molecules e.g. NH3, (CH3)NH2,(CH3)3N, C6H5NH2(aniline), HCO3, H2O,... 3
Strong () and Weak Acid (Base) z Strong acid (base) Strong acid: completely dissociated into H+ & anions in water (e g HCl HNO3 H2SO4 HBr HI HClO4 (e.g. HCl, HNO ) 3, H2SO4, HBr, HI, HClO4, …) Strong base: completely dissociated into OH- & cations in water (all IA, IIA cations’ hydroxide, e.g. NaOH, Ba(OH)2, …) z Weak acid (base) Weak acid (base) Weak acid: partially dissociated, majority as molecules ¾ e.g. HF, HClO, HCN H,S HCOOH (f i id) CH COOH ( ti 2S, HCOOH (formic acid), CH3COOH (acetic acid), HCO3-, H2O, … Weak base: partially dissociated majority as molecules Weak base: partially dissociated, majority as molecules ¾ e.g. NH3, (CH3)NH2, (CH3)3N, C6H5NH2 (aniline), HCO3-, H2O, … 3
Conjugate Acid-Base Pair Acd:HA+H2O→H2O++A Base:B+H2O→HB++OH HA and A, or HB* and B, are called conjugate acid ba ase paIr. Q: Write the conjugate acid/base of species in the previous slide? Weak acid: HF HCIO. HCN. HaS HCOOH. CHaCOOH HCO3, Fe(H2O)6 Weak base: NH3, (CH3)NH2,(CH3)2NH, (CH3)3N, C6HSNH2 (aniline), HCO3, Fe(H2O)5(OH) How about strong acids? Strong base? H,o? 4
Conj gu ate Acid-Base Pair z Acid: HA + H2O Æ H3O+ + ABase: B + H2O Æ HB+ + OH- HA and A- or HB+ HA and A , or HB and B are called conjugate acid and B, are called conjugate acidbase pair. Q: Write the conjugate acid/base of species in the previous slide? previous slide? ¾ Weak acid: HF, HClO, HCN, H2S, HCOOH, CH3COOH, HCO3- Fe(H2O)6 HCO 2+ 3 , Fe(H2O)6 ¾ Weak base: NH3, (CH3)NH2, (CH3)2NH, (CH3)3N, C6H5NH2 (aniline), HCO3-, Fe(H2O)5(OH)+ ¾ How about strong acids? Strong base? H2O? 4
Poly-protic acid Define: contain more than one mole ionizable hydronium ions e.g. H2SO4, H2CO3, H3PO4, H2C2O Is it a strong acid or weak acid? For strong acid, each step is fully dissociation For weak acid, each step is partial dissociation Identify the conjugate acid-base pairs of each dissociation equation 5
Poly-protic acid z Define contain more than one mole Define: contain more than one mole ionizable hydronium ions. e.g. H2SO4, H2CO3, H3PO4, H2C2O4 ¾ Is it a strong acid or weak acid? Is it a strong acid or weak acid? ¾ For strong acid, each step is fully dissociation. ¾ For weak acid, each step is partial dissociation. Identify the conjugate acid-base pairs of each dissociation equation dissociation equation. 5