The 6294.orgistry of Oxygen The 6294.orgistry of Ozone Oxygen as an Oxidizing certified dealer
Peroxides Methods of prepare O2 The 6294.orgistry of Sulfur
The result of distinctions in the strength of X-X and also X=X Bonds The result of distinctions in the Electronegativities the Sulfur and Oxygen The impact of differences in the ability of Sulfur and also Oxygen to increase Their Valence shell

The 6294.orgistry ofOxygen

Oxygen is the most abundant facet on this planet. Theearth"s crust is 46.6% oxygen through weight, the seas are 86%oxygen through weight, and also the environment is 21% oxygen by volume. Thename oxygen originates from the Greek trunk oxys,"acid," and also gennan, "to form orgenerate." Thus, oxygen literally method "acidformer." This name was presented by Lavoisier, who noticedthat compounds wealthy in oxygen, such together SO2 and P4O10,dissolve in water to offer acids.

The electron configuration of one oxygen atom 2s22p4 argues that neutral oxygen atom canachieve an octet of valence electron by sharing 2 pairs ofelectrons to form an O=O twin bond, as displayed in the figurebelow.

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According to this Lewis structure, every one of the electron in theO2 molecule room paired. The compound must thereforebe diamagnetic it must be repelled through amagnetic field. Experimentally, O2 is uncovered to be paramagneticit isattracted come a magnetic field. This have the right to be explained by assumingthat there space two unpaired electron in the

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* antibondingmolecular orbitals of the O2 molecule.


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This photograph shows the the liquid O2 is so strongly attracted to a magnetic field that it will bridge the gap in between the poles of a horseshoe magnet.

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At temperatures listed below -183oC, O2condenses to kind a liquid with a characteristic light blue colorthat outcomes from the absorb of light v a wavelength of630 nm. This absorb is not watched in the gas phase and also isrelatively weak also in the liquid due to the fact that it needs that threebodies two O2 molecules and also a photon collidesimultaneously, which is a an extremely rare phenomenon, also in theliquid phase.

The 6294.orgistry ofOzone

The O2 molecule is not the only elemental type ofoxygen. In the presence of lightning or another resource of aspark, O2 molecule dissociate to form oxygen atoms.


spark
O2(g) " width="17" height="9"> 2 O(g)

These O atoms deserve to react v O2 molecules to formozone, O3,


O2(g) + O(g) " width="17" height="9"> O3(g)

whose Lewis framework is displayed in the figurebelow.

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Oxygen (O2) and also ozone (O3) are examplesof allotropes (from the Greek definition "inanother manner"). By definition, allotropes are differentforms of one element. Due to the fact that they have various structures,allotropes have different 6294.orgical and physical properties (seetable below).

Properties of allotrope of Oxygen


Oxygen (O2 ) Ozone (O3 )
Melting point -218.75oC -192.5oC
Boiling Point -182.96oC -110.5oC
Density (at 20oC) 1.331 g/L 1.998 g/L
O-O link order 2 1.5
O-O bond length 0.1207 nm 0.1278 nm

Ozone is an turbulent compound through a sharp, pungent odor thatslowly decomposes come oxygen.


3 O3(g) " width="17" height="9"> 3 O2(g)

At short concentrations, ozone deserve to be relatively pleasant. (Thecharacteristic clean odor linked with summer thunderstorms isdue come the formation of small amounts of O3.)

Exposure come O3 at greater concentrations leads tocoughing, rapid beating of the heart, chest pain, and also generalbody pain. In ~ concentrations over 1 ppm, ozone is toxic.

One the the characteristic properties of ozone is its abilityto absorb radiation in the ultraviolet section of the spectrum (> 300 nm), thereby offering a filter that protects us fromexposure come high-energy ultraviolet radiation emitted through the sun.We have the right to understand the prominence of this filter if we think aboutwhat happens when radiation from the sunlight is took in by our skin.

Electromagnetic radiation in the infrared, visible, andlow-energy sections of the ultraviolet spectrum ( 3 and CF2Cl2,which had been offered as refrigerants and as propellants in aerosolcans, were beginning to accumulate in the atmosphere. In thestratosphere, in ~ altitudes the 10 come 50 km over the earth"ssurface, chlorofluorocarbons decompose to type Cl atoms andchlorine oxides such as ClO once they absorb sunlight. Cl atomsand ClO molecules have an odd variety of electrons, as shown inthe figure below.

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As a result, this substances space unusually reactive. In theatmosphere, they react v ozone or through the oxygen atom thatare needed to form ozone.


Cl + O3 " width="17" height="9"> ClO + O2
ClO + O " width="17" height="9"> Cl + O2

Molina and also Rowland postulated the these building materials wouldeventually deplete the ozone shield in the stratosphere, withdangerous ramifications for organic systems that would certainly beexposed to enhanced levels that high-energy ultraviolet radiation.

Oxygen together anOxidizing agent

Fluorine is the only element that is an ext electronegative thanoxygen. As a result, oxygen gains electrons in basically all its6294.orgical reactions. Each O2 molecule must get fourelectrons to meet the octets the the two oxygen atoms withoutsharing electrons, as shown in the number below.

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Oxygen thus oxidizes metals to type salts in which theoxygen atoms room formally present as O2- ions. Rustforms, because that example, as soon as iron reacts with oxygen in the presenceof water to provide a salt that formally has the Fe3+and O2- ions, through an typical of three water moleculescoordinated to every Fe3+ ion in this solid.


H2O
4 Fe(s) + 3 O2(g) " width="17" height="9"> 2 Fe2O3(s) 3 H2O

Oxygen likewise oxidizes nonmetals, such as carbon, come formcovalent compound in i beg your pardon the oxygen formally has an oxidationnumber the -2.


C(s) + O2(g) " width="17" height="9"> CO2(g)

Oxygen is the perfect instance of one oxidizing agentbecause it boosts the oxidation state of practically any substancewith which that reacts. In the food of that reactions, oxygen isreduced. The substances that reacts with are thus reducingagents.

Peroxides

It takes four electrons to minimize an O2 molecule toa pair that O2- ions. If the reaction stops after the O2molecule has got only two electrons, the O22-ion shown in the figure below is produced.

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This ion has actually two more electrons 보다 a neutral O2molecule, which method that the oxygen atoms should share only asingle pair of bonding electron to achieve an octet the valenceelectrons. The O22- ion is dubbed the peroxideion due to the fact that compounds the contain this ion space unusually wealthy inoxygen. They room not simply oxides they room (hy-)peroxides.

The easiest method to prepare a peroxide is come react salt orbarium steel with oxygen.


2 Na(s) + O2(g) " width="17" height="9"> Na2O2(s)
Ba(s) + O2(g) " width="17" height="9"> BaO2(s)

When this peroxides are enabled to react v a strong acid,hydrogen peroxide (H2O2) is produced.


BaO2(s) + 2 H+(aq) " width="17" height="9"> Ba2+(aq) + H2O2(aq)

The Lewis framework of hydrogen peroxide consists of an O-Osingle bond, as displayed in the number below.

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The VSEPR concept predicts that the geometry about each oxygenatom in H2O2 must be bent. But thistheory can not predict even if it is the 4 atoms need to lie in thesame aircraft or even if it is the molecule need to be visualized as lyingin two intersecting planes. The experimentally determinedstructure of H2O2 is presented in the figurebelow.

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The H-O-O bond edge in this molecule is only slightly largerthan the angle between a pair of adjacent 2p atomicorbitals ~ above the oxygen atom, and also the angle between the planesthat type the molecule is slightly bigger than the tetrahedralangle.

The oxidation number of the oxygen atoms in hydrogen peroxideis -1. H2O2 can thus act as anoxidizing agent and capture two much more electrons to type a pair ofhydroxide ions, in i beg your pardon the oxygen has actually an oxidation number of-2.


H2O2 + 2 e- " width="17" height="9"> 2 OH-

Or, it deserve to act together a reducing agent and lose a pair ofelectrons to kind an O2 molecule.


H2O2 " width="17" height="9"> O2 + 2 H+ + 2 e-

Reactions in i m sorry a compound concurrently undergoes bothoxidation and also reduction are dubbed disproportionationreactions. The assets of the disproportionation of H2O2are oxygen and also water.


2 H2O2(aq) " width="17" height="9"> O2(g) + 2 H2O(l)

The disproportionation that H2O2 is anexothermic reaction.


2 H2O2(aq) " width="17" height="9"> O2(g) + 2 H2O(l)
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H
o = -94.6 kJ/mol H2O

This reaction is fairly slow, however, in the absence of acatalyst, such together dust or a metal surface. The principal uses ofH2O2 revolve approximately its oxidizing ability.It is provided in dilute (3%) services as a disinfectant. In moreconcentrated remedies (30%), it is used as a bleaching agent forhair, fur, leather, or the wood pulp offered to make paper. In veryconcentrated solutions, H2O2 has been usedas rocket fuel because of the ease through which that decomposes togive O2.

Methods ofPreparing O2

Small quantities of O2 gas have the right to be prepared in anumber that ways.

1. By decomposing a dilute solution of hydrogen peroxide withdust or a steel surface together the catalyst.


2 H2O2(aq) " width="17" height="9"> O2(g) + 2 H2O(l)

2. By reaction hydrogen peroxide with a solid oxidizingagent, such as the permanganate ion, MnO4-.


5 H2O2(aq) + 2 MnO4-(aq) + 6 H+(aq) " width="17" height="9"> 2 Mn2+(aq) + 5 O2(g) + 8 H2O(l)

3. By happen an electric current through water.


electrolysis
2 H2O(l) " width="17" height="9"> 2 H2(g) + O2(g)

4. By heating potassium chlorate (KClO3) in thepresence the a catalyst until it decomposes.


MnO2
2 KClO3(s) " width="17" height="9"> 2 KCl(s) + 3 O2(g)

The 6294.orgistry ofSulfur

Because sulfur is directly listed below oxygen in the routine table,these aspects have comparable electron configurations. Together a result,sulfur forms many compounds that are analogs that oxygen compounds,as displayed in the table below. Instances in this table present how theprefix thio- deserve to be provided to show compounds in whichsulfur replace instead replace an oxygen atom. The thiocyanate (SCN-)ion, for instance, is the sulfur-containing analog of the cyanate(OCN-) ion.

Oxygen Compounds and Their Sulfur Analogs


Oxygen Compounds Sulfur Compounds
Na2O (sodium oxide) Na2S (sodium sulfide)
H2O (water) H2S (hydrogen sulfide)
O3 (ozone) SO2 (sulfur dioxide)
CO2 (carbon dioxide) CS2 (carbon disulfide)
OCN- (cyanate) SCN- (thiocyanate)
OC(NH2)2 (urea) SC(NH2)2 (thiourea)

There are 4 principal differences between the 6294.orgistry ofsulfur and also oxygen.

1. O=O dual bonds are much stronger 보다 S=S twin bonds.

2. S-S single bonds are almost twice as strong as O-O singlebonds.

3. Sulfur (EN = 2.58) is much less electronegativethan oxygen (EN = 3.44).

4. Sulfur can increase its valence shell to hold more than eightelectrons, but oxygen cannot.

These look at minor differences have vital consequencesfor the 6294.orgistry of these elements.

The effect ofDifferences in the stamin of X-X and also X=X Bonds

The radius that a sulfur atom is about 60% larger than the ofan oxygen atom.

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As a result, that is harder for sulfur atom to come closeenough with each other to form bonds. S=S double bonds room thereforemuch weaker 보다 O=O twin bonds.

Double bonds in between sulfur and also oxygen or carbon atoms deserve to befound in link such together SO2 and also CS2 (seefigure below). But these dual bonds are much weaker 보다 theequivalent double bonds come oxygen atom in O3 or CO2.The link dissociation enthalpy for a C=S dual bond is 477kJ/mol, for example, vice versa, the link dissociation enthalpy because that aC=O dual bond is 745 kJ/mol.

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Elemental oxygen consists of O2 molecules in whicheach atom completes that octet of valence electrons by sharing twopairs of electrons with a single neighboring atom. Because sulfurdoes not type strong S=S dual bonds, elemental sulfur usuallyconsists that cyclic S8 molecules in which every atomcompletes its octet through forming single bonds to two neighboringatoms, as shown in the number below.

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S8 molecules can pack to kind more 보다 onecrystal. The many stable kind of sulfur is composed of orthorhombiccrystals the S8 molecules, which are often discovered nearvolcanoes. If these crystals are heated till they melt and also themolten sulfur is climate cooled, an allotrop of sulfur consistingof monoclinic crystals of S8 molecule isformed. This monoclinic crystals gradually transform themselvesinto the an ext stable orthorhombic framework over a period oftime.

The propensity of an facet to form bonds to itself is dubbed catenation(from the Latin catena, "chain"). Becausesulfur develops unusually strong S-S solitary bonds, that is better atcatenation than any element except carbon. Together a result, theorthorhombic and also monoclinic develops of sulfur space not the onlyallotropes the the element. Allotropes of sulfur likewise exist thatdiffer in the size of the molecules that kind the crystal. Cyclicmolecules that contain 6, 7, 8, 10, and 12 sulfur atoms areknown.

Sulfur melts in ~ 119.25oC to kind a yellow liquidthat is less viscous 보다 water. If this liquid is heated come 159oC,it turns into a dark red liquid that cannot be poured native itscontainer. The viscosity that this dark red liquid is 2000 timesgreater 보다 that that molten sulfur since the cyclic S8molecules open up up and link together to type long chains of asmany together 100,000 sulfur atoms.


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16 K(s) + S8(s) " width="17" height="9"> 8 K2S(s)

This is no the only product that deserve to be obtained, however. Avariety that polysulfide ions with a charge of -2 can be producedthat differ in the variety of sulfur atom in the chain.

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The impact ofDifferences in the Electronegativities that Sulfur and also Oxygen

Because sulfur is much much less electronegative than oxygen, it ismore likely to type compounds in i beg your pardon it has actually a positiveoxidation number (see table below).

Common Oxidation Numbers for Sulfur


Oxidation Number Examples
-2 Na2S, H2S
-1 Na2S2, H2S2
0 S8
+1 S2Cl2
+2 S2O32-
+21/2 S4O62-
+3 S2O42-
+4 SF4, SO2, H2SO3, SO32-
+5 S2O62-
+6 SF6, SO3, H2SO4, SO42-

In theory, sulfur deserve to react through oxygen to form either SO2or SO3, who Lewis frameworks are given in the figurebelow.


SO2
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SO3
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In practice, combustion of sulfur compounds provides SO2,regardless of whether sulfur or a compound of sulfur is burned.

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S8(s) + 8 O2(g) " width="17" height="9"> 8 SO2(g)
CS2(l) + 3 O2(g) " width="17" height="9"> CO2(g) + 2 SO2(g)
3 FeS2(s) + 8 O2(g) " width="17" height="9"> Fe3O4(s) + 6 SO2(g)

Although the SO2 created in this reactions shouldreact through O2 to kind SO3, the price of thisreaction is very slow. The rate of the switch of SO2into SO3 have the right to be greatly increased by adding anappropriate catalyst.


V2O5/K2O
2 SO2(g) " width="17" height="9"> 2 SO3(g)

Enormous quantities of SO2 are produced by industryeach year and also then convert to SO3, which have the right to be usedto create sulfuric acid, H2SO4. In theory,sulfuric acid have the right to be made by dissolving SO3 gas inwater.


SO3(g) + H2O(l) " width="17" height="9"> H2SO4(aq)

In practice, this is not convenient. Instead, SO3is took in in 98% H2SO4, wherein it reactswith the water to type additional H2SO4molecules. Water is then added, together needed, to keep theconcentration of this solution between 96% and 98% H2SO4by weight.

Sulfuric mountain is by much the most necessary industrial6294.orgical. That has even been said that there is a directrelationship between the amount of sulfuric mountain a countryconsumes and its standard of living. An ext than 50% of thesulfuric acid developed each year is used to do fertilizers. Therest is supplied to do paper, artificial fibers and also textiles,insecticides, detergents, feed additives, dyes, drugs,antifreeze, paints and also enamels, linoleum, artificial rubber,printing inks, cellophane, photographic film, explosives,automobile batteries, and also metals such together magnesium, aluminum,iron, and also steel.

Sulfuric acid dissociates in water to give the HSO4-ion, i m sorry is recognized as the hydrogen sulfate, or bisulfate, ion.


A range of salts have the right to be formed by instead of the H+ions in sulfuric acid with positively charged ions, such together theNa+ or K+ ions.


Sulfurous mountain doesn"t dissociate in water to as an excellent extentas sulfuric acid, but it is still feasible to change the H+ions in H2SO3 with positive ions to formsalts.


Sulfuric acid and also sulfurous acid space both examples of a classof compounds known as oxyacids, because they areliterally acids the contain oxygen. Since they room negativeions (or anions) that contain oxygen, the SO32-and SO42- ion are known as oxyanions.The Lewis structures of few of the oxides of sulfur the formoxyacids or oxyanions are offered in the table below.


One of these oxyanions deserves distinct mention. This ion,which is known as the thiosulfate ion, is developed by the reactionbetween sulfur and the sulfite (SO32-) ion.


The impact ofDifferences in the ability of Sulfur and Oxygen to expand TheirValence shell

The electron configurations of oxygen and sulfur are usuallywritten together follows.


Although this notation shows the similarity in between theconfigurations the the two elements, that hides one importantdifference that allows sulfur to broaden its valence covering to holdmore 보다 eight electrons.

Oxygen reacts through fluorine to type OF2.


The reaction stop at this point because oxygen deserve to hold onlyeight electron in the valence shell, as displayed in the figurebelow.

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Sulfur reacts through fluorine to form SF4 and also SF6,shown in the number below, because sulfur can increase its valenceshell to organize 10 or also 12 electrons.


S8(s) + 16 F2(g) " width="17" height="9"> 8 SF4(g)
S8(s) + 24 F2(g) " width="17" height="9"> 8 SF6(g)