Ch. 15/16: Acids and Bases Definitions of Acids and Bases Conjugate Acids and Bases Amphoteric Substances
Definitions of Acids and Bases Arrhenius Most specific/exclusive definition Created by Svante Arrhenius, Swedish Acid : compound that creates H+ in an aqueous solution Base : compound that creates OH- in an aqueous solution HNO3 H+ + NO3- NaOH Na+ + OH-
Definitions of Acids and Bases Bronsted-Lowry A bit more general and more common Created by two scientists around the same time (1923) Acid: Molecule or ion that is a H+ donor Base: Molecule or ion that is a H+ acceptor HCl + H2O H3O+ + Cl- Does not include strong bases
Definitions of Acids and Bases Lewis The most general and least traditional Defined by electrons instead of H+ Created by same scientist who electron-dot diagrams are named after Acid: atom, ion, or molecule that accepts electron pair to form covalent bond Base: atom, ion or molecule that donates and electron pair to form covalent bond :NH3 + Ag+ [Ag(NH3)2]1+ BF3 + :NH3 BF3-NH3
Acids or Bases? C5H5N Mg(OH)2 HF NH3 H2CO3 H2SO4 KOH CH3NH2 HC2H3O2 HI base (weak) Mg(OH)2 base (strong) HF acid (weak) NH3 H2CO3 H2SO4 acid (strong) KOH base (strong) CH3NH2 base (weak) HC2H3O2 acid (weak) HI
Acid – Base Reactions Identify the acids and bases of the following reactions C6H5NH2 + H2O C6H5NH3+ + OH- B A HNO3 + H2O H3O+ + NO3- A B HCH3COO + H2O H3O+ + CH3COO- A B BF3 + F- BF4 A B
Acid-Base Reactions Amphoteric Substances Can act as either acid or base depending on what they are mixed with Example: Water, HSO4-
Conjugate Acid-Base Pairs Conjugate acids and bases are always created by a B-L reaction (are products) Conjugate acid A base that has gained a H+ Has an extra hydrogen NH4+, C6H5NH3+, H3O+ Conjugate base An acid that has lost a H+ Missing a hydrogen Ex: H2PO4-, OH-, Cl-
Identify the parts of these reactions C6H5NH2 + H2O C6H5NH3+ + OH- base acid CA CB HNO3 + H2O H3O+ + NO3- acid base CA CB HCH3COO + H2O H3O+ + CH3COO- acid base CA CB NH3 + H2O NH4+ + OH- base acid CA CB