Nonmetallic Elements and Their Compounds Notes
Hydrogen Production
- Hydrogen can be produced through various reactions:
- Steam reforming of propane: C3H8 (g) + 3H2O (g) \rightarrow 3CO (g) + 7H2 (g)
- Reaction of carbon with steam: C (s) + H2O (g) \rightarrow CO (g) + H2 (g)
- Reaction of zinc with hydrochloric acid: Zn (s) + 2HCl (aq) \rightarrow ZnCl2 (aq) + H2 (g)
Binary Hydrides of Representative Elements
- Binary hydrides can be classified based on their structure and bonding:
- Discrete molecular units (e.g., CH4, NH3, H_2O, HF)
- Polymeric structure: covalent compounds (e.g., (BeH2)n)
- Ionic compounds (e.g., LiH, NaH, KH, CaH_2)
Isotopes of Hydrogen
- Hydrogen has three isotopes: protium (^1H), deuterium (^2H or D), and tritium (^3H or T).
- Kinetic Isotope Effect
- Illustrates the difference in reaction rates due to isotopic substitution.
- Example:
- CH3COOH (aq) \rightleftharpoons CH3COO^- (aq) + H^+ (aq), K_a = 1.8 \times 10^{-5}
- CH3COOD (aq) \rightleftharpoons CH3COO^- (aq) + D^+ (aq), K_a = 6 \times 10^{-6}
Hydrogenation
- Hydrogenation is the addition of hydrogen to compounds containing multiple bonds.
- Example: C=C + H2 \rightarrow H-C-C-H (requires a catalyst such as Pt on Al2O_3).
The Hydrogen Economy
- Hydrogen as a fuel:
- 2H2 (g) + O2 (g) \rightarrow 2H_2O (l)
- Fuel values of common fuels (kJ/g):
- Wood (pine): 18
- Coal: 31
- Crude oil: 45
- Gasoline: 48
- Natural gas: 49
- Hydrogen: 142
- Metallic hydrogen exists under extreme pressure, such as in the interior of Jupiter.
- Jupiter's interior composition includes:
- Insulating molecular hydrogen
- Metallic molecular hydrogen
- Metallic atomic hydrogen
- Rock core
Phase Diagram of Carbon
- Carbon exists in different phases depending on pressure (P) and temperature (t).
- Diamond: High pressure phase.
- Graphite: Stable at lower pressures.
- Vapor and Liquid phases.
- At 3300 °C and 2 \times 10^4 atm, carbon can be in liquid phase.
- C (diamond) \rightarrow C (graphite), \Delta G^o = -2.87 kJ
Synthetic Gas from Coal
- Coal can be converted to synthetic gas through several reactions:
- C (s) + H2O (g) \rightarrow CO (g) + H2 (g)
- C (s) + 2H2 (g) \rightarrow CH4 (g)
- CO (g) + 2H2 (g) \rightarrow CH3OH (l)
Common Compounds of Nitrogen
- Table of nitrogen compounds with different oxidation numbers, formulas, and structures:
- Ammonia (NH_3): -3 oxidation number
- Hydrazine (N2H4): -2 oxidation number
- Hydroxylamine (NH_2OH): -1 oxidation number
- Nitrogen (dinitrogen) (N_2): 0 oxidation number
- Nitrous oxide (N_2O): +1 oxidation number
- Nitric oxide (NO): +2 oxidation number
- Nitrous acid (HNO_2): +3 oxidation number
- Nitrogen dioxide (NO_2): +4 oxidation number
- Nitric acid (HNO_3): +5 oxidation number
Production of Phosphorus
- Phosphorus is produced from calcium phosphate:
- 2Ca3(PO4)2 (s) + 10C (s) + 6SiO2 (s) \rightarrow 6CaSiO3 (s) + 10CO (g) + P4 (s)
- White phosphorus can be converted to red phosphorus:
- nP4 \text{ (white phosphorus)} \xrightarrow{3000 \degree C} (P4)_n \text{ (red phosphorus)}
- Reaction of phosphorus with oxygen:
- P4 (s) + 5O2 (g) \rightarrow P4O{10} (s)
Oxides of Phosphorus
- Phosphorus forms two common oxides: P4O6 and P4O{10}.
Common Phosphorus-Containing Oxoacids
- Phosphorous acid (H3PO3) structure.
- Hypophosphorous acid (H3PO2) structure.
- Phosphoric acid (H3PO4) structure.
- Triphosphoric acid (H5P3O_{10}) structure.
Ammonium Nitrate – The Explosive Fertilizer
- Ammonium nitrate can decompose explosively:
- NH4NO3 (g) \rightarrow N2O (g) + 2H2O (g) \text{ at } T > 250 \degree C
- 2NH4NO3 (g) \rightarrow 2N2 (g) + 4H2O (g) + O_2 (g) \text{ at } T > 300 \degree C
Oxides
- Oxides can be:
- Basic oxides
- Amphoteric oxides
- Acidic oxides
- Oxide ion: O^{2-}
- Peroxide ion: O_2^{2-}
- Superoxide ion: O_2^{-}
- Reactions of superoxide and peroxide ions in water:
- O2^- (aq) + H2O (l) \rightarrow HO_2 (aq) + OH^- (aq)
- O2^{2-} (aq) + 2H2O (l) \rightarrow O_2 (g) + 4OH^- (aq)
- 4O2^- (aq) + 2H2O (l) \rightarrow 3O_2 (g) + 4OH^- (aq)
Ozone
- Ozone formation: 3O2 (g) \rightleftharpoons 2O3 (g), \Delta G^0 = 326.8 kJ
- Ozone is a powerful oxidizing agent.
- Ozone can be produced by electrical discharge.
Frasch Process
- The Frasch process is used to extract sulfur.
- Involves using compressed air and superheated water to melt and extract sulfur from underground deposits.
Common Compounds of Sulfur
- Table of sulfur compounds with different oxidation numbers, formulas, and structures:
- Hydrogen sulfide (H_2S): -2 oxidation number
- Sulfur (S_8): 0 oxidation number
- Disulfur dichloride (S2Cl2): +1 oxidation number
- Sulfur dichloride (SCl_2): +2 oxidation number
- Sulfur dioxide (SO_2): +4 oxidation number
- Sulfur trioxide (SO_3): +6 oxidation number
Properties of the Halogens
- Table summarizing properties of halogens (F, Cl, Br, I):
- Valence electron configuration:
- F: 2s^22p^5
- Cl: 3s^23p^5
- Br: 4s^24p^5
- I: 5s^25p^5
- Melting and boiling points.
- Appearance.
- Atomic and ionic radii.
- Ionization energy.
- Electronegativity.
- Standard reduction potential.
- Bond enthalpy.
Electrolytic Production of Fluorine
- Fluorine is produced by electrolysis:
- 2F^- \rightarrow F_2 (g) + 2e^-
- 2H^+ + 2e^- \rightarrow H_2 (g)
- Overall: 2HF \rightarrow H2 (g) + F2 (g)
Laboratory Production of Chlorine Gas
- Chlorine gas can be produced in the laboratory by reacting manganese dioxide with hydrochloric acid:
- MnO2 (s) + 2H2SO4 (aq) + 2NaCl (aq) \rightarrow MnSO4 (aq) + Na2SO4 (aq) + 2H2O (l) + Cl2 (g)
Chlorine Production by the Chlor-Alkali Process
- Chlorine is produced by electrolysis of sodium chloride solution:
- 2Cl^- (aq) \rightarrow Cl_2 (g) + 2e^-
- 2Na^+ (aq) + 2e^- \rightarrow 2Na/Hg
- 2NaCl (aq) \rightarrow 2Na/Hg (g) + Cl_2 (g)
Common Compounds of Halogens
- Table of common halogen compounds:
- Hydrogen halides (HF, HCl, HBr, HI)
- Oxides (e.g., Cl2O, ClO2, Cl2O7, I2O5)
- Oxoacids (e.g., HClO, HClO2, HClO3, HClO4, HIO3, H5IO6)