ACIDS, BASES, & SALTS

Properties of Acids Sour taste Electrolytes: - aqueous solns conduct an electric current React with bases to form water and a salt (Neutralization Reaction) React with most metals to produce H2(g) Acids turn litmus red

Electrolyte Substance that dissolves in H2O to produce a solution that conducts an electric current Acids, bases, & salts are electrolytes – form ions in H2O NaCl(s)  Na+1(aq) + Cl-1(aq)

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

Properties of Bases Bitter taste Slippery or soapy feeling Electrolytes React with acids to produce water and a salt Bases turn litmus blue

Formulas of Acids 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

Formulas of Bases Format: MOH where M is a metal Ex: NaOH, Ca(OH)2 Exception: NH3 and NH4+1 CH3OH is NOT a base. WHY?

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 - S NO NO Yes - A Yes - A NO Yes - B Yes - S NO NO Yes - S Yes - B Yes - A Yes - A Yes - B Yes - S NO NO

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

Water & self-ionization H2O(l) + H2O(l)  H3O+1(aq) + OH-1(aq) H3O+1 = hydronium ion OH-1 = hydroxide ion H2O(l)  H+1(aq) + OH-1(aq) H+1 and H3O+1 used interchangeably H+1 called proton or hydrogen ion

Self-ionization of water

Arrhenius Acid Substance that contains hydrogen & ionizes to produce H+1 ions in aqueous solution HCl(g)  H+1(aq) + Cl-1(aq) HNO3  H+1(aq) + NO3-1(aq)

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

Arrhenius Salt Electrolytes where H+1 not only positive ion and OH-1 not only negative ion formed in aqueous solution Ex: NaCl, CaBr2,KNO3, NH4I

Salts in Water (ionic compounds) NaCl(s)  Na+1(aq) + Cl-1(aq) CaBr2(s)  Ca+2(aq) + 2Br-1(aq) KNO3(s)  K+1(aq) + NO3-1(aq) NH4I(s)  NH4+1(aq) + I-1(aq)

Arrhenius Model has limitations Don’t always use H2O as solvent Arrhenius model only applies when H2O is solvent Doesn’t explain all cases: NH3 doesn’t contain OH-1 but it produces OH-1

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

Bronsted-Lowry Base Base = proton acceptor OH-1 is a 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

Amphoteric Substance that acts as both acid & base H2O is amphoteric HX(g) + H2O(l)  H3O+1 + X-1 (base) NH3 + H2O  NH4+1 + OH-1 (acid)

Water is amphoteric!

Naming Acids & Bases

Hydro + stem of nonmetal + ic Naming Binary Acids Hydro + stem of nonmetal + ic HF = ? HCl = ? H2S = ? Hydrofluoric acid Hydrochloric acid Hydrosulfic acid

Naming Ternary Acids Name derived from polyatomic anion (see Table E) Replace –ite with –ous , add acid HNO2 is nitrous acid Replace –ate with –ic, add acid HNO3 is nitric acid

Ternary Acids polyatomics with S and P, make stem long again H3PO4 = phosphoric acid, not phosphic acid H2SO4 = sulfuric acid, not sulfic acid H2SO3 = sulfurous acid, not sulfous acid SEE TABLE K

Name the metal + hydroxide NaOH = ? Ca(OH)2 = ? Mg(OH)2 = ? Naming Bases Name the metal + hydroxide NaOH = ? Ca(OH)2 = ? Mg(OH)2 = ? Sodium hydroxide Calcium hydroxide Magnesium hydroxide