ACIDS, BASES, & SALTS

Acids verses Bases Properties of ACIDS: Properties of BASES: bitter taste classified as electrolyte react with acids (neutralization rxn) slippery or soapy feeling bases turn litmus paper blue sour taste classified as electrolyte react with bases (neutralization reaction) react with most metals to produce H2(g) (SR rxn) acids turn litmus paper red

Chemical Formulas Formula of Acid: Formula of Base: format: HX where X = non-metal/poly ion format: XCOOH exceptions: H2O2 H2O format: MOH where M is metal ex: NaOH, Ca(OH)2 exceptions: NH3 NH4+1 OH -1 Why is CH3OH NOT a base?

Which metals react with acids? see Table J: all metals above H2 react with acids undergo SR rxns (metal replaces H in acid) Cu, Ag, and Au do NOT react with acids

Electrolyte substance that dissolves in H2O to produce aqueous soln that conducts electric current 3 substances fit this description: acids, bases and salts

All 3 subs dissociate (ionize) in H2O Electrolytes All 3 subs dissociate (ionize) in H2O ACID: HCl(s)  H+1(aq) + Cl-1(aq) BASE: NaOH(s)  Na+1(aq) + OH-1(aq) SALT: NaCl(s)  Na+1(aq) + Cl-1(aq) H2O(l) H2O(l) H2O(l)

Identify the Electrolytes NaCl C2H5OH H2SO4 NaOH C6H12O6 CaI2 HF Mg(OH)2 C3H7OH CCl4 HNO3 C5H12 K3PO4 CH3OCH3 LiOH HI (NH4)2SO4 C12H22O11 Yes - salt NO NO Yes - acid Yes - acid NO Yes – base & salt Yes - salt NO NO Yes - salt Yes – salt & base Yes - acid Yes - acid Yes – base & salt Yes - base NO NO

Acid-Base Theories: Arrhenius Theory acids/bases ionize in water based on type ions produced when acid/base mixed with water limitations Bronstead-Lowry Theory aka: alternative theory based on acid/base being proton donor/receiver NO limitations

Arrhenius Acid substance that contains hydrogen & ionizes to produce H+1 ions in (aq) soln HCl  H+1(aq) + Cl-1(aq) CH3COOH  H+1(aq) + CH3COO-1(aq) H2O(l) H2O(l)

Arrhenius Base substance that contains hydroxide group & ionizes to produce OH-1 ions in (aq) soln NaOH(s)  Na+1(aq) + OH-1(aq) H2O(l)

Arrhenius Salt electrolyte where H+1 not only (+) ion and OH-1 not only (-) ion formed in aqueous solution ex: CaBr2(s)  Ca+2(aq) + 2Br-1(aq) KNO3(s)  K+1(aq) + NO3-1(aq) H2O(l) H2O(l)

Arrhenius Model has limitations Arrhenius model ONLY applies when H2O is solvent don’t always use H2O as solvent doesn’t explain why NH3 (and its ion:NH4+1) are bases: doesn’t contain OH-1 but will produce OH-1 ions in (aq) soln NH3(g)  NH4+1(aq) + OH-1(aq) H2O(l)

Alternate Theory: Bronsted-Lowry Acid is a proton donor all Arrhenius acids = Bronsted-Lowry Acids H+1 HX(g) + H2O(l)  H3O+1(aq) + X-1(aq) H+1 forms molecule-ion bond with water molecule to form H3O+1 (hydronium ion)

Bronsted-Lowry Acids HCl + H2O  H3O+1 + Cl-1 H2SO4 + H2O  H3O+1 + HSO4-1 HSO4-1 + H2O  H3O+1 + SO4-2 H+1 H+1

Bronsted-Lowry Base bases are proton acceptors NH3 + H2O  NH4+1 + OH-1 explains why NH3 is a base!

Amphoteric substance that acts as BOTH an acid & a base

Water is amphoteric! HX(g) + H2O(l)  H3O+1 + X-1 (base) NH3 + H2O  NH4+1 + OH-1 (acid)