T3 OXYGEN Flashcards

1
Q

Why does oxygen have a strong tendency to have an oxidation state of –2?

A

Oxygen tends to have an oxidation state of –2 because it is two electrons short of achieving a closed-shell configuration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What distinguishes oxygen’s oxidizing power from other group 16 elements?

A

Only oxygen forms doubly-bonded O2 molecules, giving it strong oxidizing power compared to other elements in the group.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do ionization energies vary within group 16 elements?

A

Ionization energies decrease down group 16 due to the increase in atomic radius.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What trend do electronegativities follow within group 16?

A

Electronegativities are high and decrease down group 16, with oxygen being the second most electronegative element.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does larger size affect polarizability and interactions?

A

Larger size leads to higher polarizability, resulting in an increase in dispersion interactions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens to electron affinities as you descend group 16?

A

Electron affinities are high and decrease down the group, except for oxygen due to increased interelectronic repulsions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why does the oxidizing power decrease down group 16?

A

The decrease in electron affinity and hydrogen leads to a decrease in oxidizing power down the group.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does oxygen’s natural occurrence differ from other chalcogens?

A

Oxygen is unique as the only gas among chalcogens, forming diatomic O2 molecules, unlike other elements which prefer single bonds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What causes the unique behavior of O2 molecules?

A

Various factors contribute, including higher oxidation power, negative total electron affinity, and the ability to form double bonds due to lower atomic size.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why does oxygen form ionic metal oxides while other chalcogens form covalent compounds?

A

Oxygen’s low polarizability and small size lead to its ability to form ionic metal oxides, unlike sulfides, selenides, and tellurides with a strong covalent character.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What percentage of Earth’s atmosphere does oxygen make up?

A

Oxygen makes up about 21% of Earth’s atmosphere, primarily originating from photosynthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How can oxygen be obtained in the laboratory?

A

Oxygen can be obtained by thermal decomposition of KClO3 or catalyzed decomposition of hydrogen peroxide in the lab.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the industrial method for obtaining oxygen?

A

Oxygen is obtained industrially by fractional distillation of liquid air, based on the difference in boiling points of N2 and O2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the most stable oxidation state of oxygen?

A

The most stable oxidation state of oxygen is –2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does pH affect the oxidizing power of O2 and H2O2?

A

The oxidizing power of both O2 and H2O2 decreases as pH is increased.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is peroxide unstable in both basic and acidic conditions?

A

Peroxide (O.S. = –1) is unstable due to disputes in both basic and acidic conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What types of bonds can oxygen form?

A

Oxygen can typically form two single bonds or one double bond and can act as a Lewis base to form coordinate covalent bonds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Provide an example of oxygen forming three equivalent covalent bonds.

A

[H3O]+ and [O(HgCl)3]+ are examples where oxygen forms three equivalent covalent bonds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Colors of the group 16?

A

O - Blue pale gass
S - Yellow solid
Se - Red solid
Te - Brown solid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the physical state of oxygen below 90 K?

A

Below 90 K, oxygen condenses to a pale blue liquid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How it increase the size in the group?

A

down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How it increase the ionization energy and electronegativity in the group?

A

up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How it increase the MP and BP in the group?

A

down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What property characterizes O2?

A

O2 is paramagnetic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the two allotropes of oxygen?

A

Oxygen exists as O2 (dioxygen) and O3 (ozone).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How can different polymorphs of solid oxygen be achieved?

A

By increasing pressure, different polymorphs of solid oxygen can be achieved. At pressures > 10 GPa, a red solid containing molecules of the third most important allotrope of oxygen, O8, exists.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How is O2’s paramagnetism explained?

A

Molecular orbital (MO) theory explains O2’s paramagnetism due to its unpaired electrons. The bond order (8-4)/2 = 2 in O2 and its charged species [O2]+, [O2]–, and [O2]2– are also explained by MO theory.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What distinguishes the 1g state of O2?

A

The 1g state has a long lifetime and is much more reactive than triplet O2. It exhibits electrophilic character as it possesses an empty π* orbital.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What electron configuration corresponds to the most stable state of O2?

A

The 3Sg – state corresponds to the most stable electron configuration according to Hund’s rule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the major applications of O2?

A

O2 is used in metallurgy, steel production, synthesis of HNO3 from NH3, medical oxygen therapy, and respiratory purposes for astronauts and divers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How is ozone (O3) produced?

A

O3 is produced by passing a stream of O2 through a 10- to 20-kV electric field.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the bond order of O3?

A

The bond order of O3 is 3/2, with each O–O bond being equivalent.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the molecular structure of O3?

A

O3 has an angular shape with diamagnetic properties. It exhibits two resonance forms in its Lewis structure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the applications of O3 due to its high oxidizing power?

A

O3 is used for water purification, eliminating microbes and pathogens in various environments. However, its commercial applications are doubted due to toxicity concerns.

31
Q

How is ozone formed in the stratosphere?

A

Ozone is formed in the stratosphere by photolysis of O2 with UV-B and UV-C radiation, following the Chapman cycle.

32
Q

What is the Chapman cycle?

A

The Chapman cycle describes the mechanism of O3 formation and decomposition, maintaining constant O3 and O2 concentrations and absorbing UV radiation.

33
Q

How do reactive chlorine atoms contribute to ozone depletion?

A

Reactive chlorine atoms catalyze the decomposition of O3 into O2, leading to ozone depletion. Each chlorine atom can destroy up to 50,000 O3 molecules before being quenched.

33
Q

What causes ozone depletion?

A

Chlorofluorocarbons (CFCs) and similar substances used in refrigeration systems are responsible for ozone depletion. They generate reactive chlorine atoms in the stratosphere, which catalyze the decomposition of O3.

34
Q

What is the role of ozone in the atmosphere?

A

Ozone absorbs life-threatening UV radiation in the atmosphere, protecting life on Earth.

35
Q

What factors contribute to the formation of the ozone hole?

A

Factors such as the presence of UV-C and UV-B radiation, low O2 concentration above 25-30 km, and the presence of reactive chlorine atoms contribute to the formation of the ozone hole.

36
Q

What is the bond length of O3 compared to O2 and H2O2?

A

The bond length of O3 lies between that of O2 (121 pm) and H2O2.

37
Q

What is the ozonide anion, and how is it formed?

A

Adding 1 e– to O3 forms the ozonide anion, O3–, with a total bond order of 5/2. This increases the O–O distance compared to O3.

38
Q

How does ozone’s high oxidizing power contribute to its applications?

A

Ozone’s high oxidizing power allows it to effectively purify water and eliminate microbes and pathogens, making it valuable for various applications. However, concerns about its toxicity limit its commercial use.

39
Q

What are oxides?

A

Oxides are binary compounds of oxygen, except with fluorine, which is called fluoride.

40
Q

What are ionic oxides, and what structures do they have?

A

Ionic oxides, formed with metals, have 3D structures with high melting and boiling points. Examples include antifluorite structures with alkali metals (M+), and NaCl structures with M2+.

41
Q

What are covalent oxides, and what are their properties?

A

Covalent oxides, formed with light non-metals and metals with high oxidation states, are volatile molecular compounds. Examples include molecular oxides of non-metals (C, N, P, S) with non-extended structures and low melting and boiling points.

42
Q

What are low-dimensional oxides, and why do they form?

A

Low-dimensional oxides, formed with heavy non-metals, have structures such as chains and planes. They form due to the presence of the inert pair, which is stereochemically active.

43
Q

What are some examples of high-valent molecular oxides?

A

Examples include Mn2O7, Tc2O7, RuO4, OsO4, and XeO4, which are important in oxidation reactions in organic chemistry but are toxic due to their volatility.

44
Q

How do oxides exhibit acid-base reactivity?

A

Oxides can be acidic, basic, or amphoteric depending on their behavior towards acids and bases.

45
Q

How is the amphoteric character observed in oxides?

A

Amphoteric character is observed in oxides like BeO and those of some elements of groups 13 and 14, which lie at the frontier between acidic and basic oxides.

45
Q

What characterizes the covalent oxides of non-metals?

A

Covalent oxides of non-metals in low oxidation states are neutral (e.g., N2O), while in high oxidation states, they are acidic

46
Q

What factors determine the acidic/basic character of transition metal oxides?

A

In transition metals, the acidic/basic character depends on the oxidation state: low oxidation states give rise to basic oxides, intermediate states to amphoteric oxides, and high oxidation states to acidic oxides.

47
Q

How does the structure of water contribute to its properties?

A

The tetrahedral arrangement of water molecules and hydrogen bonding lead to properties like high surface tension, melting and boiling points, capillarity force, specific heat, and heat of vaporization.

47
Q

What are the properties of water?

A

Water is an odorless, tasteless liquid with a pale blue color. It has an angular molecular structure, strong hydrogen bonding, and high heat capacity.

48
Q

What is the significance of water’s hydrogen bonds?

A

Hydrogen bonds in water contribute to its large surface tension, high melting and boiling points, capillarity force, specific heat, and heat of vaporization.

49
Q

What is water’s role as a solvent?

A

Water is a good solvent due to its polarity, making it miscible with many substances and facilitating chemical reactions.

49
Q

How does water regulate Earth’s weather?

A

Water’s high heat capacity and heat of vaporization allow it to regulate Earth’s weather by absorbing temperature fluctuations.

50
Q

What is unique about water’s density?

A

Water reaches its maximum density at 3.98°C and expands upon freezing, explaining why ice floats on water.

51
Q

How does water react with certain elements?

A

Elements more electropositive than hydrogen (e.g., Li, Na, K) displace hydrogen from water to form hydroxides in a violent reaction.

52
Q

How is water formed and decomposed?

A

Water is formed by the direct reaction between hydrogen and oxygen or by the electrolysis of water. It decomposes into oxygen and hydrogen by electrolysis.

53
Q

What is the domain structure of water?

A

The domain structure of water is tetrahedral, with an H–O–H angle of 104.5° and an H–O distance of 95.84 pm.

54
Q

Why is water transparent to UV-Vis radiation but not to IR radiation?

A

Water’s O–H bonds absorb in the IR region, making water vapor a significant greenhouse gas.

55
Q

What is the role of water in biological systems?

A

Water is essential for life, serving as a solvent for biochemical reactions and providing structural support to cells.

56
Q

What is the structure of pure hydrogen peroxide?

A

Pure hydrogen peroxide (H2O2) is a viscous bluish liquid with an angular non-planar structure.

56
Q

Why is hydrogen peroxide unstable against distmutation in acidic and basic media?

A

Hydrogen peroxide is unstable due to dismutation reactions, which are slow but can be catalyzed by various substances.

57
Q

Why does hydrogen peroxide have a non-planar structure?

A

Hydrogen peroxide’s non-planarity minimizes electrostatic repulsion between lone pairs of oxygen atoms and hinders molecule rotation around the O–O bond.

58
Q

How is the stability of hydrogen peroxide maintained in commercial solutions?

A

Commercial solutions of hydrogen peroxide are diluted (up to 30%) and stored in opaque bottles in the fridge to avoid decomposition accelerated by light.

59
Q

What substances can catalyze the dismutation of hydrogen peroxide?

A

Substances with redox pairs having reduction potentials between 1.76 V (reduction of H2O2 to H2O) and 0.69 V (reduction of O2 to H2O2) can catalyze hydrogen peroxide dismutation.

60
Q

How is hydrogen peroxide produced industrially?

A

Industrial production of hydrogen peroxide involves organic reactions with anthraquinone derivatives, followed by spontaneous oxidation in air.

61
Q

What are the main uses of hydrogen peroxide?

A

Hydrogen peroxide is used as a bleaching agent in the paper industry, cleaning old paints, disinfectants, hair bleaching, wastewater treatment, and rocket propellants.

62
Q

What are some applications of hydrogen peroxide in analytical chemistry?

A

Hydrogen peroxide is used to identify chromate ions by forming deep blue Cr(VI) oxide peroxide species.

63
Q

How does hydrogen peroxide contribute to waste-water treatment?

A

Hydrogen peroxide is used in waste-water treatment as an oxidant to degrade organic pollutants.

64
Q

What is the significance of hydrogen peroxide’s role in the paper industry?

A

Hydrogen peroxide is used as a bleaching agent in the paper industry to remove lignin and other impurities from wood pulp.

65
Q

What is hydrogen peroxide’s role in rocket propulsion?

A

Concentrated hydrogen peroxide is used as a propellant in rockets, either alone or in combination with fuels, due to its ability to decompose and produce oxygen.

66
Q

Describe the oxygen transport mechanism in vertebrates.

A

Oxygen is transported by hemoglobin in red blood cells, which binds to oxygen in the lungs and releases it to tissues. Myoglobin stores oxygen in muscles.

66
Q

Why is hydrogen peroxide handled with care?

A

Hydrogen peroxide is corrosive and can cause skin and eye irritation, even when diluted, requiring proper protective measures during handling.

67
Q

How is oxygen involved in biological processes?

A

Oxygen is essential for life, found in biomolecules like carbohydrates, fatty acids, proteins, and nucleic acids, and is involved in photosynthesis and cellular respiration.

68
Q

What role does manganese play in photosynthesis?

A

Manganese in photosynthesis forms the active site of the oxygen evolving complex (OEC), which oxidizes water to produce dioxygen.

69
Q

How does hemoglobin bind oxygen?

A

Hemoglobin binds oxygen to its iron-containing heme groups, inducing conformational changes that increase its affinity for subsequent oxygen molecules.

70
Q

What is cooperative binding in hemoglobin?

A

Cooperative binding in hemoglobin occurs when the binding of one oxygen molecule increases the affinity for subsequent molecules, facilitating oxygen transport.

71
Q

What are the structural differences between myoglobin and hemoglobin?

A

Myoglobin is a monomer found in muscles, while hemoglobin is a tetramer found in red blood cells, but both contain iron-containing heme groups.

72
Q

How does oxygen binding affect the color of hemoglobin?

A

Oxygen binding to hemoglobin oxidizes iron from Fe2+ to Fe3+, changing its color from bluish red to bright red.

73
Q

What role does oxygen play in aerobic respiration?

A

In aerobic respiration, glucose reacts with oxygen to produce carbon dioxide, water, and energy stored as ATP molecules.