Oxides, Hydroxides, Acids, Salts

Inorganic nomenclature - purpose

System to name compounds uniquely based on composition and oxidation state. IUPAC systematic, Stock, traditional common names all used in IMAT.

Oxidation number - definition

Charge atom would have if electrons assigned to more electronegative atom. Rules: free element 0, F -1, O usually -2 (except peroxide -1, superoxide -1/2, OF2 +2), H +1 with nonmetals -1 with metals, alkali +1, alkaline earth +2. Sum = charge of species.

Stock system vs traditional vs IUPAC - when to use

Stock: iron(III) oxide = Fe2O3. Traditional: ferric oxide. IUPAC: diiron trioxide. IMAT uses Stock most, but know traditional: -ous lower, -ic higher oxidation state. Use Stock to specify oxidation number.

Cation nomenclature

Metal loses electrons: Na+ sodium, Ca2+ calcium, Fe2+ iron(II) or ferrous, Fe3+ iron(III) or ferric, Cu+ copper(I) cuprous, Cu2+ copper(II) cupric, NH4+ ammonium.

Anion nomenclature - simple

Nonmetal gains electrons: Cl- chloride, O2- oxide, S2- sulfide, N3- nitride. Polyatomic: OH- hydroxide, CN- cyanide, O2^2- peroxide, O2^- superoxide.

Binary compounds naming rule

Electropositive first, electronegative second with -ide suffix. NaCl sodium chloride, MgO magnesium oxide, Al2O3 aluminium oxide, CO carbon monoxide, CO2 carbon dioxide, N2O dinitrogen monoxide.

Oxides - definition and general formula

Compounds of oxygen with another element. General: metal oxide MxOy where O -2. Nonmetal oxide also. Classification by acid-base behavior.

Oxides - types overview - glossary

Basic oxides: metal oxides (Na2O, CaO, FeO) basic. Acidic oxides: nonmetal oxides (CO2, SO2, SO3, N2O5) acidic aka acid anhydrides. Amphoteric: Al2O3, ZnO, PbO, Cr2O3, BeO react both. Neutral: CO, NO, N2O neither acid nor base. Peroxide: O2^2- (H2O2, Na2O2). Superoxide: O2^- (KO2).

Basic oxides - definition and examples

Metal + O, ionic, from metals low electronegativity (Group 1,2, transition low oxidation). Examples: Na2O, K2O, CaO, BaO, MgO, FeO, Cu2O. Properties: basic, react with water -> hydroxide, with acids -> salt + water.

Basic oxide + water reaction - formula

Na2O + H2O -> 2 NaOH, CaO + H2O -> Ca(OH)2, K2O + H2O -> 2 KOH. When to use: Form alkali/alkaline hydroxide. Highly exothermic for Group1.

Basic oxide + acid reaction - formula

CaO + 2 HCl -> CaCl2 + H2O, Na2O + H2SO4 -> Na2SO4 + H2O. General: basic oxide + acid -> salt + water. When to use: Neutralization, prepare salt.

Acidic oxides - definition and examples - acid anhydride

Nonmetal oxide or high oxidation metal oxide. Examples: CO2, SO2, SO3, N2O3, N2O5, P2O5 (P4O10), SiO2, Cl2O7, CrO3, Mn2O7. Called acid anhydrides because add water -> acid.

Acidic oxide + water reaction - formula

CO2 + H2O

Acidic oxide + base reaction - formula

CO2 + 2 NaOH -> Na2CO3 + H2O, CO2 + NaOH -> NaHCO3, SO3 + Ca(OH)2 -> CaSO4 + H2O. General: acidic oxide + base -> salt + water. When to use: Scrubbing, lime water test CO2 -> CaCO3 precipitate.

Amphoteric oxides - definition and list must memorize

React with both acids and bases. Must memorize: Al2O3, ZnO, PbO, PbO2, BeO, Cr2O3, SnO, SnO2. Properties: insoluble, show both behaviors.

Amphoteric oxide + acid reaction

Al2O3 + 6 HCl -> 2 AlCl3 + 3 H2O, ZnO + 2 HCl -> ZnCl2 + H2O. Behaves as base.

Amphoteric oxide + base reaction

Al2O3 + 2 NaOH + 3 H2O -> 2 Na[Al(OH)4] sodium tetrahydroxoaluminate, ZnO + 2 NaOH + H2O -> Na2[Zn(OH)4] sodium tetrahydroxozincate. Behaves as acid. When to use: Identify amphoteric.

Neutral oxides - list

CO carbon monoxide, NO nitric oxide, N2O nitrous oxide. Neither acid nor base, don't form salt with water. Properties: CO toxic, NO signaling.

Peroxides and superoxides - nomenclature

Peroxide O2^2- O -1: H2O2 hydrogen peroxide, Na2O2 sodium peroxide. Superoxide O2^- O -1/2: KO2 potassium superoxide. Dioxide vs peroxide distinction: BaO2 barium peroxide not dioxide.

Peroxide reactions

Na2O2 + 2 H2O -> 2 NaOH + H2O2, 2 Na2O2 + 2 CO2 -> 2 Na2CO3 + O2 (used in submarines).

Hydroxides - definition and general formula

Compounds M(OH)n, contain OH- group. Metal hydroxide. Nomenclature: sodium hydroxide NaOH, calcium hydroxide Ca(OH)2, iron(III) hydroxide Fe(OH)3. Traditionally base.

Hydroxides - classification by solubility

Strong soluble bases (alkalis): Group1 hydroxides LiOH NaOH KOH RbOH CsOH fully soluble strong, Group2 Ba(OH)2 Sr(OH)2 Ca(OH)2 moderately, Mg(OH)2 weak low soluble. Others: insoluble weak bases Fe(OH)3, Al(OH)3 etc.

Strong bases list IMAT must memorize

NaOH KOH LiOH RbOH CsOH, Ba(OH)2 Sr(OH)2 Ca(OH)2 (alkaline). Fully dissociate: NaOH -> Na+ + OH-.

Weak bases / insoluble hydroxides

Fe(OH)2, Fe(OH)3, Al(OH)3, Zn(OH)2, Cu(OH)2, NH4OH (NH3 aq). Partial dissociation or precipitate.

Hydroxide properties - Arrhenius base

Release OH- in water, bitter, slippery, pH>7, turn red litmus blue, phenolphthalein pink. Concentrated caustic corrosive.

Amphoteric hydroxides - list and behavior

Al(OH)3, Zn(OH)2, Pb(OH)2, Cr(OH)3, Be(OH)2, Sn(OH)2. React with acids and strong bases. Must memorize for IMAT.

Amphoteric hydroxide + acid

Al(OH)3 + 3 HCl -> AlCl3 + 3 H2O, Zn(OH)2 + 2 HCl -> ZnCl2 + 2 H2O. As base.

Amphoteric hydroxide + base

Al(OH)3 + NaOH -> Na[Al(OH)4], Zn(OH)2 + 2 NaOH -> Na2[Zn(OH)4] + 2 H2O. As acid forming complex.

Hydroxide + acidic oxide -> salt + water

Ca(OH)2 + CO2 -> CaCO3 + H2O (lime water test), 2 NaOH + SO3 -> Na2SO4 + H2O. General base + acidic oxide.

Thermal decomposition of hydroxides

Insoluble hydroxides decompose on heating: M(OH)n -> MO + H2O. Example Cu(OH)2 -> CuO + H2O (black), 2 Fe(OH)3 -> Fe2O3 + 3 H2O. Alkali hydroxides stable except: 2 NaOH -> Na2O + H2O at very high T.

Preparation of hydroxides

1) Basic oxide + water: CaO + H2O -> Ca(OH)2. 2) Metal + water: 2 Na + 2 H2O -> 2 NaOH + H2, Ca + 2 H2O -> Ca(OH)2 + H2. 3) Salt + base precipitation: FeCl3 + 3 NaOH -> Fe(OH)3↓ + 3 NaCl.

Acids - three definitions glossary

Arrhenius: releases H+ in water. Brønsted-Lowry: donates H+ (acid) to base acceptor. Lewis: accepts electron pair (acid) base donates pair. IMAT uses Brønsted most.

Hydracids (binary acids) - definition and list

Acids of H + nonmetal without O: HF hydrofluoric, HCl hydrochloric, HBr hydrobromic, HI hydroiodic, H2S hydrosulfuric (dihydrosulfide), HCN hydrocyanic. Naming hydro- + nonmetal root + -ic acid.

Oxyacids (ternary acids) - definition and list

H + nonmetal + O: H2CO3 carbonic, HNO3 nitric, HNO2 nitrous, H2SO4 sulfuric, H2SO3 sulfurous, H3PO4 phosphoric, H3PO3 phosphorous, HClO HClO2 HClO3 HClO4 hypochlorous, chlorous, chloric, perchloric.

Acid nomenclature - IUPAC vs traditional - rules

Binary: hydro + element + ic -> hydrochloric acid. Oxyacids: highest oxidation -ic (H2SO4 sulfuric), lower -ous (H2SO3 sulfurous), more O per- -ic (HClO4 perchloric), less O hypo- -ous (HClO hypochlorous). IUPAC: add -ic with oxidation number: H2SO4 tetraoxosulfuric(VI) acid.

Strong acids list IMAT must memorize - 7

HCl, HBr, HI, HNO3, H2SO4 (first dissociation strong), HClO4, HClO3. All others weak. Memorize: 3 hydrohalic (except HF weak), 2 oxyhalic per/chloric, nitric, sulfuric.

Weak acids list

HF, H2CO3, H2S, HCN, HNO2, H2SO3, H3PO4, CH3COOH acetic, all organic acids. Partial dissociation.

Acid strength - Ka, pKa, pH formulas

HA

Diprotic and triprotic acids - dissociation steps

H2SO4: H2SO4 -> H+ + HSO4- strong, HSO4-

Acid properties - general

Sour, pH

Acid + metal reaction - formula and condition

Metal + acid -> salt + H2, only metals above H: Zn + 2 HCl -> ZnCl2 + H2, Mg + H2SO4 -> MgSO4 + H2, 2 Al + 6 HCl -> 2 AlCl3 + 3 H2. Cu, Ag, Au no reaction with non-oxidizing acids. Nitric acid no H2 gives NOx.

Acid + base neutralization - formula

HCl + NaOH -> NaCl + H2O, H2SO4 + 2 KOH -> K2SO4 + 2 H2O, general HA + BOH -> salt + water. Net ionic H+ + OH- -> H2O ΔH=-57 kJ/mol.

Acid + basic oxide

2 HCl + CaO -> CaCl2 + H2O, 2 HNO3 + MgO -> Mg(NO3)2 + H2O.

Acid + carbonate/bicarbonate - CO2 test

2 HCl + CaCO3 -> CaCl2 + H2O + CO2↑, HCl + NaHCO3 -> NaCl + H2O + CO2↑. Effervescence test for carbonate.

Acid anhydride concept - relation to oxyacids

Acidic oxide + water = oxyacid, reverse oxyacid -> acidic oxide + water on heating. Example H2CO3 -> CO2 + H2O, H2SO3 -> SO2 + H2O, 2 HNO3 -> N2O5 + H2O. When to use: Prepare acidic oxides.

Nitric acid special oxidizing behavior

HNO3 never gives H2 with metals. Dilute with active metal -> N2O, NH4NO3; moderate -> NO; concentrated -> NO2. Example Cu + 4 HNO3 conc -> Cu(NO3)2 + 2 NO2 + 2 H2O, 3 Cu + 8 HNO3 dilute -> 3 Cu(NO3)2 + 2 NO + 4 H2O.

Sulfuric acid special - concentrated oxidizing and dehydrating

Conc H2SO4 oxidizing: Cu + 2 H2SO4 conc -> CuSO4 + SO2 + 2 H2O, C + 2 H2SO4 conc -> CO2 + 2 SO2 + 2 H2O. Dehydrating: sucrose C12H22O11 -> 12 C + 11 H2O (charring). Dilute behaves as normal acid.

Salts - definition and formation overview

Ionic compounds from acid-base neutralization. Cation from base, anion from acid. General formation: acid + base, acid + metal, acid + basic oxide, base + acidic oxide, salt + acid, salt + base.

Salt nomenclature - rules

Cation first then anion: NaCl sodium chloride, CaCO3 calcium carbonate, FeSO4 iron(II) sulfate or ferrous sulfate, Fe2(SO4)3 iron(III) sulfate ferric, NH4NO3 ammonium nitrate. Acid salts include hydrogen: NaHCO3 sodium hydrogen carbonate or sodium bicarbonate, NaHSO4 sodium hydrogen sulfate. Basic salts include OH: Mg(OH)Cl magnesium hydroxychloride.

Types of salts - glossary

Normal salt: all H replaced ex NaCl Na2SO4. Acid salt: contains acidic H ex NaHCO3 KHSO4 NaH2PO4. Basic salt: contains OH ex Mg(OH)Cl Al(OH)SO4. Double salt: two cations same anion ex KAl(SO4)2 alums. Complex salt: complex ion ex K4[Fe(CN)6]. Mixed salt: two anions.

Salt formation equations - 6 methods

1) Acid+base: HCl+NaOH->NaCl+H2O. 2) Acid+metal: 2HCl+Zn->ZnCl2+H2. 3) Acid+basic oxide: 2HCl+CaO->CaCl2+H2O. 4) Base+acidic oxide: 2NaOH+CO2->Na2CO3+H2O. 5) Salt+acid: CaCO3+2HCl->CaCl2+CO2+H2O (stronger acid displaces weaker). 6) Salt+base: CuSO4+2NaOH->Cu(OH)2+Na2SO4 precipitation.

Solubility rules - must memorize for IMAT

Soluble: Group1 salts, NH4+ salts, nitrates NO3- all soluble, acetates, chlorates, perchlorates. Chlorides Br- I- soluble except Ag+ Pb2+ Hg2^2+. Sulfates soluble except BaSO4 PbSO4 CaSO4 slightly, Ag2SO4 slightly. Carbonates phosphates sulfides hydroxides insoluble except Group1 and NH4+, Ca(OH)2 slightly.

Salt hydrolysis - concept

Salt of strong acid + strong base = neutral pH≈7 NaCl. Strong acid + weak base = acidic pH

Hydrolysis equations - formulas

Acidic: NH4+ + H2O

Acid salts - amphiprotic behavior

HCO3- can act acid HCO3- -> CO3^2- + H+ and base HCO3- + H+ -> H2CO3. pH = (pKa1+pKa2)/2 independent of concentration. Example NaHCO3 pH≈8.3 basic, NaH2PO4 pH≈4.5 acidic.

Thermal decomposition of salts - patterns

Carbonates: CaCO3 -> CaO + CO2 (Group1 except Li stable). Bicarbonates: 2 NaHCO3 -> Na2CO3 + CO2 + H2O. Nitrates: 2 KNO3 -> 2 KNO2 + O2 (alkali), 2 Pb(NO3)2 -> 2 PbO + 4 NO2 + O2, AgNO3 -> Ag + NO2 + O2. Chlorates: 2 KClO3 -> 2 KCl + 3 O2. Hydroxides of heavy metals -> oxide + water.

Double displacement and precipitation - principle

AB + CD -> AD + CB, occurs if precipitate, gas, or weak electrolyte forms. Use solubility rules to predict precipitate. Example AgNO3 + NaCl -> AgCl↓ + NaNO3, BaCl2 + Na2SO4 -> BaSO4↓ + 2 NaCl.

Units and constants for acids/bases/salts

pH dimensionless, [H+] mol/L M, Ka mol/L, pKa dimensionless, Kw=1.0e-14 at 25°C (mol^2/L^2), molar mass g/mol, solubility g/L or mol/L. STP.

Glossary - key terms for this chapter

Anhydride: oxide that forms acid/base with water. Alkali: soluble strong base Group1. Base anhydride: basic oxide. Acid salt: contains ionizable H. Basic salt: contains OH. Normal salt: neutral. Deliquescent: absorbs water. Efflorescent: loses water. Hygroscopic: absorbs moisture.

Reactivity series for acid reactions - must memorize

K > Na > Ca > Mg > Al > Zn > Fe > Sn > Pb > H > Cu > Hg > Ag > Au. Metals above H liberate H2 from non-oxidizing acids. More reactive displaces less from salt.

Oxidation states in oxides/hydroxides/acids/salts - examples

FeO Fe +2, Fe2O3 Fe +3, H2SO4 S +6, H2SO3 S +4, HNO3 N +5, HNO2 N +3, HClO Cl +1, HClO2 +3, HClO3 +5, HClO4 +7, KMnO4 Mn +7, K2Cr2O7 Cr +6, Na2O2 O -1.

Common IMAT traps in inorganic nomenclature

Trap: Fe3O4 magnetite is mixed FeO*Fe2O3 iron(II,III) oxide not iron(III) oxide. Trap: N2O5 is dinitrogen pentoxide not nitrogen pentoxide. Trap: H2O2 is hydrogen peroxide not dioxide. Trap: Na2O2 sodium peroxide not dioxide. Trap: FeSO4 iron(II) sulfate vs Fe2(SO4)3 iron(III).