Biological and Industrial Nitrogen Cycle

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Questions and Answers

Which compound is formed as a result of the reaction between PCl3 and Cl2?

H3PO3

HCl

PCl5 (correct)

H3PO4

What is the primary role of H3PO4 in agriculture?

It is crucial for the production of fertilizers. (correct)

It is used for fabric softening.

It removes elemental mercury.

It acts as a small-scale oxidizing agent.

Which of the following oxides is classified as an ionic metal oxide?

NiO

MgO (correct)

SiO2

ReO3

What kind of oxide is formed by the reaction of SO2 with water?

Weak acid Signup and view all the answers

Which element does not behave as a typical metal in Group 16?

Oxygen Signup and view all the answers

What property of ozone makes it significant in the atmosphere?

It absorbs UV radiation. Signup and view all the answers

Which compound is commonly used in paint removers?

Na3PO4 Signup and view all the answers

What is the oxidation state of phosphorus in P4O10?

+5 Signup and view all the answers

Which of the following elements in Group 15 is classified as a metal?

Bismuth Signup and view all the answers

What is the oxidation state range for nitrogen compounds?

-3 to 5 Signup and view all the answers

Which oxide is produced from the reaction of nitrogen dioxide and water?

HNO3 Signup and view all the answers

What is the primary industrial use of ammonia (NH3) produced through the Haber Process?

Fertilizers Signup and view all the answers

In the biological nitrogen cycle, what is the final product of denitrifying bacteria processing nitrates (NO3-)?

Nitrogen gas Signup and view all the answers

What end product is formed from the biological nitrogen fixation process in bacteria?

NH3 Signup and view all the answers

What is the overall reaction of the Oswald Process for producing nitric acid (HNO3)?

NH3(g) + O2(g) → NO(g) + H2O(g) Signup and view all the answers

What type of compounds are all the chlorides in Group 5A?

Molecular compounds Signup and view all the answers

Which of the following nitrogen oxides has the highest oxidation state for nitrogen?

N2O5 Signup and view all the answers

Which allotrope of phosphorus is characterized by a tetrahedral structure and high reactivity?

White Phosphorus Signup and view all the answers

Which of the following oxyacids of phosphorus is triprotic?

Phosphoric acid (H3PO4) Signup and view all the answers

What is the main characteristic of the triple bond in molecular nitrogen (N2)?

It provides high stability Signup and view all the answers

What is one application of hydrazine (N2H4)?

Rocket propellant Signup and view all the answers

What is the specific role of nitrogen-fixing bacteria in the nitrogen cycle?

They reduce atmospheric N2 to NH3 Signup and view all the answers

What is the resulting product when white phosphorus reacts with oxygen?

P4O10 Signup and view all the answers

Which hydride of nitrogen is primarily used for the production of strong oxidizing agents?

Nitric acid (HNO3) Signup and view all the answers

What is the primary reaction product when SO3(g) reacts with H2O(l)?

H2SO4(aq) Signup and view all the answers

Which of the following compounds is a weak acid?

H2SO3 Signup and view all the answers

What is the role of V2O5/K2O in the synthesis of sulfur dioxide to sulfur trioxide?

Catalyst Signup and view all the answers

Which of these compounds is NOT an important compound of sulfur?

CaSO4 Signup and view all the answers

What is the correct formula for sulfurous acid?

H2SO3 Signup and view all the answers

What type of acid is sulfuric acid categorized as?

Diprotic strong acid Signup and view all the answers

Which process is used for sulfur mining?

Frasch Process Signup and view all the answers

Which of the following oxyacids of sulfur is a significant oxidizing agent?

Peroxydisulfuric acid Signup and view all the answers

Study Notes

Biological Nitrogen Cycle

NH3, NH4+, and NO3- can be released into the surroundings and become available to plants.
Denitrifying bacteria change NO3- back to NO2-, NH3, and finally to N2.

Industrial Nitrogen Fixation

Haber Process: N2(g) + 3H2(g) → 2NH3(g) ΔH° = -92 kJ
Most NH3 produced is used in fertilizers (~70%), Nitric acid (~20%), Hydrazine, and monomers for plastics and nylons.

Important Hydrides of Nitrogen

Ammonia (NH3) is the most important hydride.
It is used to produce fertilizers, HNO3, and N2H4.
Hydrazine (N2H4) is used as a rocket propellant, in the manufacture of plastics, and in agricultural pesticides.
Monomethylhydrazine (CH3N2H3) is used as a rocket fuel.

Production of HNO3 - Oswald Process

NH3(g) + O2(g) → NO(g) + H2O(g)
2NO(g) + O2(g) → NO2(g)
3NO2(g) + H2O(l) → 2HNO3(aq) +NO(g)

HNO3

It is a strong acid and an oxidizing agent.
Reactions with metals do not produce H2.

Allotropes of Phosphorus

White Phosphorus (P4) is tetrahedral and very reactive.
Black Phosphorus has a crystalline structure and is much less reactive.
Red Phosphorus is amorphous with P4 chains.

Oxides of Phosphorus

Reactions of white phosphorus with oxygen:
- P4(s) + 3O2(g) → P4O6(l) (o.s.of P = +3)
- P4(s) + 5O2(g) → P4O10(s) (o.s.of P = +5)
Reactions of phosphorus oxides with water:
- P4O6(l) + 6H2O(l) → 4H3PO3(aq)
- P4O10(s) + 6H2O(l) → 4H3PO4(aq)

Oxyacids of Phosphorus

Phosphoric acid (H3PO4) is triprotic.
Phosphorous acid (H3PO3) is diprotic.
Hypophosphorous acid (H3PO2) is monoprotic.

ATP

Adenosine Triphosphate: a molecule that plays a key role in providing energy for metabolic processes.
ADP: Adenosine Diphosphate

Phosphorus Halides

Reactions of white phosphorus with halogens:
- P4(s) + 6X2 → 4PX3(l)
- P4(s) + 10X2 → 4PX5(s)
Examples of reactions:
- PCl3(l) + Cl2(g) ⇄ PCl5(s)
- PCl3(l) + 3H2O(l) → H3PO3(aq) + 3HCl(aq)
- PCl5(s) + 4H2O(l) → H3PO4(aq) + 5HCl(aq)

Oxides of Group 5A Elements

Nitrogen: N2O, NO, N2O3, NO2, N2O4, N2O5
Phosphorus: P4O6 & P4O10
Arsenic: As2O3 (As4O6) & As2O5
Antimony: Sb2O3 & Sb2O5
Bismuth: Bi2O3 & Bi2O5

Chlorides of Group 5A Elements

Nitrogen: only NCl3
Phosphorus: PCl3 and PCl5
Arsenic: AsCl3 and AsCl5
Antimony: SbCl3 and SbCl5
Bismuth: BiCl3

Reactions of Oxides and Chlorides

3NO2(g) + H2O(l) → 2HNO3(aq) + NO(g)
N2O5(g) + H2O(l) → 2HNO3(aq)
P4O10(s) + 6H2O(l) → 4H3PO4(aq)
As2O5(s) + 3H2O(l) → 2H3AsO4(aq)
PCl5(s) + 4H2O(l) → H3PO4(aq) + 5HCl(aq)
AsCl5(s) + 4H2O(l) → H3AsO4(aq) + 5HCl(aq)
2SbCl5(s) + 5H2O(l) → Sb2O5(s) + 10HCl(aq)

The Chemistry of Nitrogen

The triple bonds in N2 (N≡N) provide high stability.
Oxidation states range from -3 to +5.
Many reactions involving nitrogen gas are endothermic; compounds containing nitrogen decompose exothermically to the elements.
N2(g) + O2(g) → 2NO(g) ΔH° = 180 kJ
2NO2(g) → N2(g) + O2(g); ΔH° = -68 kJ
N2H4(g) → N2(g) + 2H2(g); ΔH° = -95 kJ

Nitrogen Fixation

The process of transforming N2 to other nitrogen-containing compounds.
Atmospheric fixation occurs naturally during thunderstorms:
- N2(g) + O2(g) → 2NO(g); ΔHo = 180 kJ
- 2NO(g) + O2(g) → 2NO2(g); ΔHo = -112 kJ
- 3NO2(g) + H2O(l) → 2HNO3(aq) + NO(g); ΔHo = -140 kJ

Biological Nitrogen Fixation

Fixation of atmospheric N2 by bacteria.
Some bacteria live in root nodules of plants like legumes and alfalfa.
Plants benefit directly from bacteria, while other plants benefit from the release of absorbable nitrogen (NH3, NH4+, and NO3-) when the bacteria die.

Biological Nitrogen Fixation - Steps

Atmospheric N2 is reduced to NH3 in nitrogen-fixing bacteria.
NH3 becomes NH4+ in bacterial cells and is oxidized to NO2- and then to NO3-.

Important Compounds of Phosphorus

Ca3(PO4)2 & Ca5(PO4)3F: sources of phosphorus
Ca5(PO4)3(OH): forms bones and teeth
P4O10: formation of H3PO4
H3PO4: production of fertilizers & phosphates
H2PO4- & HPO42-: phosphate buffers
Na3PO4: scouring powder and paint remover
Na5P3O10: fabric softeners
ADP & ATP: storage of metabolic energy
PCl5: precursor for lithium hexafluorophosphate (LiPF6), an electrolyte in lithium-ion batteries.

Group 16, 6A

Valence-shell configuration: ns2 np4
Nonmetals that form covalent bonds.

Oxygen

O2 makes up 21% of the Earth’s atmosphere.
Ozone (O3) exists naturally in the stratosphere.
Ozone absorbs UV light and blocks most UV radiation.
CFCs are responsible for ozone depletion.

Various Forms of Oxides

Metal oxides (ionic)
- Nonconductor: MgO
- Semiconductor: NiO
- Conductor: ReO3
- Superconductor: YBa2Cu3O7
Nonmetal oxides (covalent)
- Molecular oxides: CO2, NO, NO2, N2O, SO2, P4O10, etc.
- Covalent network oxide: SiO2

Characteristics of Oxides

Metallic oxides are basic or amphoteric (e.g., Na2O, Al2O3).
Semi-metallic oxides are mild to weakly acidic (e.g., B2O3).
Nonmetallic oxides are weak to strong acids (e.g., SO2, SO3)

Redox Properties of Water

Hydrogen peroxide (H2O2):
- A weak acid.
- Can undergo disproportionation.
- Redox properties vary depending on the environment (acidic or basic).

Sulfur

Sulfur is found in nature as a free element and in ores like galena (PbS), cinnabar (HgS), pyrite (FeS2), gypsum (CaSO4⋅2H2O), epsomite (MgSO4.7H2O), and glauberite (Na2Ca(SO4)2).

Sulfur Mining: Frasch Process

This is a method used to extract sulfur from underground deposits.

Sulfur Oxides and Oxyacids

S(s) + O2(g) → SO2(g)
2SO2(g) + O2(g) → 2SO3(g)
SO2(g) + H2O(l) → H2SO3(aq)
SO3(g) + H2O(l) → H2SO4(aq)

Sulfuric Acid

H2SO3: weak acid
H2SO4: strong acid

Production of Sulfuric Acid:

S8(s) + 8 O2(g) → 8SO2(g)
2H2S(g) + 3 O2(g) → 2SO2(g) + 2H2O(l)
FeS2(s) + 11 O2(g) → Fe2O3(s) + 8SO2(g)
2SO2(g) + O2(g) → 2SO3(g) (V2O5/K2O catalyst)
2SO3(g) + H2SO4(l) → H2S2O7(l)
H2S2O7(l) + H2O(l) → 2H2SO4(l)

Oxyacids of Sulfur

Sulfurous acid (H2SO3), Sulfuric acid (H2SO4), Disulfurous acid (H2S2O5), Polysulfuric acids (H2SO4.nSO3), Thiosulfurous acid (H2S2O2), Peroxymonosulfuric acid (H2SO5), Dithionous acid (H2S2O4), Peroxydisulfuric acid (H2S2O8), Dithionic acid (H2S2O6), Polythionic acids (H2SnO6), and Thiosulfuric acid (H2S2O3).

Important Compounds of Sulfur

H2SO4: most important compound used in the manufacture of fertilizer, soap, detergents, metal and textile processing, sugar refinery, and organic syntheses.
SF4: for fluoridation
SF6: as insulating and inert blanket
Na2S2O3: as reducing agent and complexing agent for Ag+ in photography (called “hypo”)
P4S3: in “strike-anywhere” match heads

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Description

Explore the fascinating processes of the biological and industrial nitrogen cycles. This quiz covers nitrogen fixation methods, important hydrides of nitrogen, and the production of nitric acid. Test your understanding of these concepts and their significance in agriculture and industry.