CHEM250 Final Review

Inorganic chemistry

Nitrogen oxide reactions

NO2 / N2O / N2O3 / N2O5 + H2O —> HNO3 / HNO2

Natural Nitrogen vs Phosphorus

N2: gas molecule with 1 sigma and 2 pi bonds

P4: solid molecule with 3 sigma bonds

Natural Oxygen vs Sulfur

O2: gas molecule with 1 sigma and 1 pi bond

S8: solid molecule with 2 sigma bonds

Natural Carbon vs Silicon

C2: sigma and pi bond combo (single, double, triple bonds)

Si5: tetrahedral network of sigma bonds

Key characteristics of period 2 and 3 bonds (4)

1. P2: pi bonds common as 2p orbital overlap is easy

2. P3: pi bonds not common as 3p orbital overlap is not easy

3. P3: expanded octet from d-orbitals so easy sigma bonds

4. Compounds with pi bonds are less likely to be solid

Phosphorous allotropes in order of stability

White (P4, tetrahedral), Red (P4 loses a bond and connects to make a chain), Black (more bonds break and forms sheet)

Phosphorous oxide reactions

P2O3 / P2O5 / P4O6 / P4O10 + H2O —> PO4 3-

P4 and limited oxygen

P4 + O2 —> P4O6 + H2O —> H3PO3 (-ous)

P4 and excess oxygen

P4 + xs O2 —> P4O10 + H2O —> H3PO4 (-ic)

Synthesis of P4 from rocks calcium phosphate

2Ca3(PO4)2 (s) + 6SiO2 (s) + 10C(s) —> 6CaSiO3 (l) + 10CO(g) + P4 (g)

Environmental impacts of phosphorus

Banned from detergents bc PO4 3- is not biodegradable and cannot be removed easily via water treatment

Industrial importance of phosphorus

1. Water softening / binding agent

2. Fertilizers

Pyrophosphate reaction

PO4Na2H molecules combine in condensation reaction to produce TPP 3- ligands

Industry phosphoric acid reaction

H3PO4 <-> H2PO4 - <-> HPO4 2- <-> PO4 3-

• loss of H+ each time

• Phosphoric acid and Phosphate ions are most common

Phosphorous acid

• Diprotic, weak

• Phosphite salts

• ox state = 3

• From P4O6

Phosphoric acid

• triprotic, weak

• phosphate salts

• ox state = 5

• From P4O10

Phosphorous to oxyacid salts

Natural Sulfur

Found as ores / in elemental form + has no smell (change of ox# = smell)

H2O vs H2S

H2O has hydrogen bonds, making it ordourless and liquid

H2S doesn’t, and creates a toxic smell

Claus Process Purpose

Converts H2S (g) —> S (s)

Claus Process Reactions

H2S (g) + 3/2O2 (g) —> SO2 (g) + H2O (l) | burning

SO2 (g) + 2H2S (g) —> 3S (s) + 2H2O (l) | catalyst, 200-300C

*Note ox states, disproportionate rxn

Acid Rain Reaction

S + O2 —> SO2 + H2O —> H2SO3

Acid Rain (cause, consequence, sol)

• burning exhausts from industry creates oxides that react with water to form acid

• Harms aquatic life and corrodes heritage buildings

• Use scrubbers (eg. limestone) to reduce emissions

Sulfur oxides and acid production

S + O2 + heat —> SO2

2SO2 —> 2SO3 | V2O5 catalyst, O2

SO3 + H2SO4 —> H2S2O7

H2S2O7 + H2O —> 2H2SO4

Natural Sources of group 17

Found in combination with less electronegative elements, primarily metal halides (seawater and minerals)

Halogen inter reactions

½ I2 + Cl- —> no rxn

½ Cl2 + I- —> Cl- + ½ I2

2Br- + ½ Cl —> Br2 + Cl-

2HF —> F2 + H2 (electrolyte = molten KHF2)

Ox and Acid strength trend

Increasing oxidation state = Stronger acid = Salts are stronger oxidizing agent

Halogens with higher ox # will have more pull on the O, making H easy to remove

Chlorine compound usage

Bleach, Pool disinfectant, PVC, Rocket fuel

Chlorine Oxyacid production

Cl2 + H2O —> HOCl + HCl

Chlorine oxyacid table (compound, name, ion)

Oxyacid comparison of P,S,Cl

P

• 2 oxyacids (state: +3, +5)

• Triprotic

S

• 2 oxyacids (state: 4,+6)

• Diprotic

Cl

• 4 oxyacids (states: +1, +3, +5, +7)

• Monoprotic

Metallic bonding

Atoms slide over each other because of e-, alloys swap metals and stay neutral

Ionic bonding