ACIDS, BASES, & SALTS

Properties of Acids 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

Formula of Acid format: HX where X = nonmetal (F, Cl, Br, I) or X = negative polyatomic ion some acids have 2 or 3 H’s ex: HF, H2S, H3PO4 exceptions: H2O2 and H2O

Properties of Bases bitter taste slippery or soapy feeling classified as electrolyte react with acids (neutralization rxn) bases turn litmus paper blue

Formula of Base format: MOH where M is metal CH3OH is NOT a base WHY? ex: NaOH, Ca(OH)2 exceptions: NH3 and NH4+1 CH3OH is NOT a base WHY?

Electrolyte substance that dissolves in H2O to produce aqueous soln that conducts electric current

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)

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 Yes - salt NO NO Yes - salt Yes - base Yes - acid Yes - acid Yes - base Yes - base NO NO

Which metals react with acids? See Table J All metals above H2 react with acids Cu, Ag, and Au do NOT react with acids

2HCl + Mg  MgCl2 + H2 Mg above H2 so reaction proceeds single replacement reaction occurs

Arrhenius Acid substance that contains hydrogen & ionizes to produce H+1 ions in (aq) soln HCl + H2O(l)  H+1(aq) + Cl-1(aq) HNO3 + H2O(l)  H+1(aq) + NO3-1(aq)

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

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)

Arrhenius Model has limitations don’t always use H2O as solvent Arrhenius model only applies when H2O is solvent doesn’t explain why NH3 is base: doesn’t contain OH-1 but produces OH-1 ions in soln NH3(g)  NH4+1(aq) + OH-1(aq)

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

Bronsted-Lowry Acids HCl + H2O  H3O+1 + Cl-1 HNO3 + H2O  H3O+1 + NO3-1 H2SO4 + H2O  H3O+1 + HSO4-1 HSO4-1 + H2O  H3O+1 + SO4-2 H+1 H+1 H+1

Bronsted-Lowry Base bases are proton acceptors OH-1 is base H+1 + OH-1  H2O not restricted to aqueous solution NH3 + H2O  NH4+1 + OH-1 NH3 is a base!

Bronsted-Lowry Acids & Bases

water: self-ionization H2O(l) + H2O(l)  H3O+1(aq) + OH-1(aq) H3O+1 = hydronium ion OH-1 = hydroxide ion OR H2O(l)  H+1(aq) + OH-1(aq) H+1 :hydrogen ion = proton H+1 & H3O+1 used interchangeably

self-ionization of water H2O (l) + H2O (l)  H3O+1 (aq) +OH-1(aq)

Acid, Base, or Neutral? all H2O contains some H+1 and some OH-1 ions pure H2O: concentrations very low neutral solution: [H+1] = [OH-1] acidic solution: H+1 > OH-1 basic solution: OH-1 > H+1

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)