COMPULSORY READINGS 11 - CDLteachingcommons.cdl.edu/avu.old/chemistry/documents...1 According to the author of the module, the compulsory readings do not infringe known copyright

C O M P U LS O R Y C O M P U LS O R Y

RE A D IN G SRE A D IN G S 11

1 According to the author of the module, the compulsory readings do not infringe known copyright.

COMPULSORY READINGS

Complete reference : Solutions: From Wikipedia, the free encyclopidia http://en.wikipedia.org/wiki/Solutions Abstract : The article addresses most of the relevant concepts in solutions. The differences between a solution and a heterogenous mixture, the intermolecular forces or attractions that hold molecules together including solvation, types of solutions, the effect of temperature and pressure on solubility, and the various concentration units are discussed. Colligative properties of solutions are briefly explained and the article provides links for further reference. Rationale: This article helps to provide the basis for further reading on the topic of solutions. It givess useful links to those concepts which are not discussed in detail in the article. Therefore, it is a useful article to study topics which will be discussed under the unit for solutions.

Complete reference : Reaction Rate : From Wikipedia, the free encyclopidia http://en.wikipedia.org/wiki/Reaction_rate Chemical Equilibrium: http://en.wikipedia.org/wiki/Chemical_equilibrium Abstract : The article on reaction rate provides important discussions on the topic itself with emphasis on the rate equation, and the factors influencing reaction rate, notably,concentration, temperature, nature of reactants, pressure, and catalyst.

The article on chemical equilibrium focuses on the equilibrium conditions of reversible reactions. It defines and explains the differences between reversible and irreversible reactions and the conditions for chemical equilibrium based on LeChateliers principle. Rationale: The two links will help you as additional study materials for the unit ‘Reaction Rate and Equilibrium’ which is covered in this module. The articles in the two links present relevant and practical examples which will strengthen your conceptual and computational skills in the topics covered.

Organic Compounds: Naming and Isomerism

R ea d i n g (s ) # 1R ea d i n g (s ) # 1

Solution - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Solutions

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SolutionFrom Wikipedia, the free encyclopedia(Redirected from Solutions)

This article is about a chemical solution; for other uses of theterm "solution", see solution (disambiguation).

In chemistry, a solution is a homogeneous mixture composed of one ormore substances, known as solutes, dissolved in another substance,known as a solvent. A common example is a solid, such as salt or sugar,dissolved in water, a liquid. Gases may dissolve in liquids, for example, carbon dioxide or oxygen inwater. Liquids may dissolve in other liquids and gases always mix with other gases [1].

Examples of solid solutions are alloys, certain minerals and polymers containing plasticizers. The ability ofone compound to dissolve in another compound is called solubility. The physical properties of compoundssuch as melting point and boiling point change when other compounds are added. Together they are calledcolligative properties. There are several ways to quantify the amount of one compound dissolved in theother compounds collectively called concentration. Examples are molality and parts per million (ppm).

Solutions should be distinguished from other non-homogeneous mixtures such as colloids andsuspensions.

Contents1 Types of solutions2 Solvents3 Solvation4 Ideal solutions5 See also6 References

Types of solutionsMany types of solutions exist, as solids, liquids and gases can be both solvent and solute, in anycombination:

Examples of SoluteGas Liquid Solid

Dissolving table salt (NaCl)in water

Dissolving table salt (NaCl) inwater


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solutions

Solvent

Gas Oxygen and other gases innitrogen (air)

Water vapor in air(humidity)

Iodine sublimates intoair

Liquid Carbon dioxide in water(carbonated water)

Ethanol (commonalcohol) in water;various hydrocarbons ineach other (petroleum)

Sucrose (table sugar) inwater; sodium chloride(table salt) in water; goldin mercury, forming anamalgam

Solid

Hydrogen dissolves rather wellin metals; platinum has beenstudied as a storage medium.This effect was used in the coldfusion experiments.

Hexane in paraffin wax,mercury in gold.

Steel, duralumin, othermetal alloys

SolventsSolvents can be broadly classified into polar and non-polar solvents. A common measure of the polarity ofa solvent is the dielectric constant. The most widely used polar solvent is water, with a dielectric constantof 78.5. Ethanol, with a dielectric constant of 24.3, has intermediate polarity. An example of a non-polarsolvent is hexane, which has a dielectric constant of 1.9. Generally polar or ionic compounds will onlydissolve in polar solvents. A simple test for the polarity of a liquid solvent is to rub a plastic rod, to inducestatic electricity. Then hold this charged rod close to a running stream of the solvent. If the path of thesolvent deviates when the rod is held close to it, it is a polar solvent. Certain molecules have polar andnon-polar regions, for example sodium dodecyl sulfate. This class of molecules (called amphipathicmolecules) includes surfactants like soaps and emulsifiers, as they have the ability to stabilize emulsions byaligning themselves on the interface between the non-polar and polar liquids, with their polar ends in thepolar liquid and their non-polar ends in the non-polar liquid.

SolvationDuring solvation, especially when the solvent is polar, a structure forms around it, which allows thesolute-solvent interaction to remain stable.

When no more of a solute can be dissolved into a solvent, the solution is said to be saturated. However, thepoint at which a solution can become saturated changes significantly with different environmental factors,such as temperature, pressure, and contamination. Raising the solubility (for example by increasing thetemperature) to dissolve more solute, and then lowering the solubility causes a solution to becomesupersaturated.

In general the greater the temperature of a solvent, the more of a given solid solute it can dissolve.However, some compounds exhibit reverse solubility, which means that as a solvent gets warmer, lesssolute can be dissolved. Some surfactants exhibit this behaviour. The solubility of liquids in liquids is


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generally less temperature-sensitive than that of solids or gases, while gases usually become less solublewith increasing temperature.

Ideal solutionsAn ideal solution is one where the interactions of the molecules of the solvent with each other are equal totheir interactions with the solutes. The properties of an ideal solution can be calculated by the linearcombination of the properties of its components.

If both solute and solvent exist in equal quantities (such as in a 50% ethanol, 50% water solution), theconcepts of "solute" and "solvent" become less relevant, but the substance that is more often used as asolvent is normally designated as the solvent (in this example, water).

See alsoMolar solutionPercentage solutionSolubility equilibriumStock solutionTotal dissolved solids is a common term in a range of disciplines, and can have different meaningsdepending on the analytical method used. In water quality, it refers to the amount of residueremaining after evaporation of water from a sample.

References

^ Streitwieser, Andrew; Heathcock, Clayton H., Kosower, Edward M. (19922). Introduction to Organic Chemistry,4th ed., Macmillan Publishing Company, New York. ISBN 0-02-418170-6.

1.

SOLUTION • Ideal solution • Aqueous solution • Solid solution • Flory-Huggins • Mixture • Suspension (chemistry) • Colloid• Phase diagram • Eutectic point • Alloy

CONCENTRATION • Saturation (chemistry) • Supersaturated • Molar solution • Percentage solution

SOLUBILITY • Solubility equilibrium • Total dissolved solids • Dissolve • Solvation • Enthalpy change of solution • Latticeenergy • Henry's law • Solubility table (data) • Solubility chart

SOLVENT (category) • Acid dissociation constant • Protic solvent • Inorganic nonaqueous solvent • Solvation • Solvationshell • List of boiling and freezing information of solvents

Partition coefficient • Polarity • Hydrophobe • Hydrophile • Lipophilic • Amphiphiles

Retrieved from "http://en.wikipedia.org/wiki/Solution"

Categories: Solutions | Homogeneous mixtures | Alchemical processes | Physical chemistry

This page was last modified 07:28, 24 March 2007.All text is available under the terms of the GNU Free Documentation License. (See Copyrights for

Articles related to solutions [hide]


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details.) Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a US-registered 501(c)(3)tax-deductible nonprofit charity.


Reaction rate - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Reaction_rate

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Reaction rateFrom Wikipedia, the free encyclopedia

'The reaction rate or rate of reaction for a reactant or product in a particular reaction is intuitively defined as how fast a reaction takes place. For example the oxidation of iron under the atmosphere is a slow reaction which can take years, the combustion of butane in a fire is a reaction that takes place in fractions of a second.' Chemical kinetics is the part of physical chemistry that studies reaction rates. The concepts of chemical kinetics are applied in many disciplines, such as chemical engineering, enzymology or environmental engineering.

Contents1 Formal definition of reaction rate2 Factors influencing rate of reaction3 Rate Equation4 Temperature dependence5 Example6 See also7 Notes8 External links

Formal definition of reaction rate

According to IUPAC's Gold Book definition[1] the reaction rate v (also r or R) for the general chemicalreaction aA + bB → pP + qQ, occurring in a closed system under constant-volume conditions, without an appreciable build-up of reaction intermediates, is defined as:

v = - \frac{1}{a} \frac{d[A]}{dt} = - \frac{1}{b} \frac{d[B]}{dt} = \frac{1}{p} \frac{d[P]}{dt} = \frac{1}{q} \frac{d[Q]}{dt}

The IUPAC[1] recommends that the unit of time should always be the second. In such a case the rate of reaction differs from the rate of increase of concentration of a product P by a constant factor (the reciprocal of its stoichiometric number) and for a reactant A by minus the reciprocal of the stoichiometric number. Reaction rate usually has the units of mol dm-3 s-1. ngi saIt is important to bear in mind that the previous definition is only valid for a single reaction, in a closed system of constant volume. This most usually implicit assumption must be stated explicitly, otherwise the definition is incorrect: If water is added to a pot containing salty water, the concentration of salt decreases, although there is no chemical reaction.

Iron rusting - a chemical reaction with a slow reaction rate.

Iron rusting - a chemical reaction with a slow reaction rate.

Wood burning - a chemical reaction with a fast reaction rate.

Wood burning - a chemical reaction with a fast reaction rate.


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For any system in general the full mass balance must be taken into account: IN - OUT + GENERATION = ACCUMULATION

F_{A0} - F_A + \int_{0}^{V} r\, dV = \frac{dN_A}{dt}

When applied to the simple case stated previously this equation reduces to: v= \frac{d[A]}{dt}

For a single reaction in a closed system of varying volume the so called rate of conversion can be is used, in order to avoid handling concentrations. It is defined as the derivative of the extent of reaction with respect to time.

\dot{\xi} =\frac{d\xi}{dt} = \frac{1}{\nu_i} \frac{dn_i}{dt} = \frac{1}{\nu_i} \left(V\frac{dC_i}{dt} + C_i \frac{dV}{dt} \right)

\scriptstyle \nu_i is the stoichiometric coefficient for substance i, \scriptstyle V is the volume of reaction and \scriptstyle C_i is the concentration of substance i.

When side products or reaction intermediates are formed, the IUPAC[1] recommends the use of the terms rate of appearance and rate of disappearance for products and reactants, respectively.

Factors influencing rate of reactionThere are several factors that affect the rate of reaction:

Concentration: Reaction rate increases with concentration, as described by the rate law and explained by collision theory. As reactant concentration increases, the frequency of collisionincreases.The nature of the reaction: Some reactions are naturally faster than others. The number of reacting species, their physical state (the particles that form solids move much more slowly than those of gases or those in solution), the complexity of the reaction and other factors can influence greatly the rate of a reaction.Temperature: Conducting a reaction at a higher temperature delivers more energy into the system and increases the reaction rate by causing more collisions between particles, as explained by collision theory. However, the main reason why it increases the rate of reaction is that more of the colliding particles will have the necessary activation energy resulting in more successful collisions (when bonds are formed between reactants). The influence of temperature is described by the Arrhenius equation. As a rule of thumb, reaction rates for many reactions double or triple for every 10 degrees Celsius increase in temperature.[2]

For example, coal burns in a fireplace in the presence of oxygen but it doesn't when it is stored at room temperature. The reaction is spontaneous at low and high temperatures but at room temperature its rate is so slow that it is negligible. The increase in temperature, as created by a match, allows the reaction to start and then it heats itself, because it is exothermic. That is valid for many other fuels, as methane, butane, hydrogen...

Solvent: Many reactions take place in solution and the properties of the solvent affect the reaction rate. The ionic strength as well has an effect on reaction rate.Pressure: The rate of gaseous reactions increases with pressure, which is, in fact, equivalent to an increase in concentration of the gas.Electromagnetic Radiation: Electromagnetic radiation is a form of energy so it may speed up the rate


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or even make a reaction spontaneous, as it provides the particles of the reactants with more energy. This energy is in one way or another stored in the reacting particles (it may break bonds, promote molecules to electronically or vibrationally excited states...) creating intermediate species that react easily.

For example when methane reacts with chlorine in the dark, the reaction rate is very slow. It can be speeded up when the mixture is put under diffused light. In bright sunlight, the reaction is explosive.

A catalyst: The presence of a catalyst increases the reaction rate (in both the forward and reverse reactions) by providing an alternative pathway with a lower activation energy.

For example, platinum catalyzes the combustion of hydrogen with oxygen at room temperature.

Isotopes: The kinetic isotope effect consists in a different reaction rate for the same molecule if it has different isotopes, usually hydrogen isotopes, because of the mass difference between hydrogen and deuterium.Surface Area: In reactions on surfaces, which take place for example during heterogeneous catalysis, the rate of reaction increases as the surface area does. That is due to the fact that more particles of the solid are exposed and can be hit by reactant molecules.Order: The order of the reaction controls how the reactant concentration affects reaction rate.

All the factors that affect a reaction rate are taken into account in the rate equation of the reaction.

Rate EquationFor a chemical reaction n A + m B → C + D, the rate equation or rate law is a mathematical expressionused in chemical kinetics to link the rate of a reaction to the concentration of each reactant. It is of the kind:

\,r = k(T)[A]^{n'}[B]^{m'}

In this equation k(T) is the reaction rate coefficient or rate constant, although it is not really a constant, because it includes all the parameters that affect reaction rate, except for concentration, which is explicitly taken into account. Of all the parameters described before, temperature is normally the more important one.

The exponents n' and m' are called reaction orders and depend on the reaction mechanism. They sometimes are the same as the stoichiometric coefficients of A and B, but not necessarily.

Stoichiometry, molecularity (the actual number of molecules colliding) and reaction order only coincide necessarily in elementary reactions, that is, those reactions that take place in just one step. The reaction equation for elementary reactions coincides with the process taking place at the atomic level, i.e. n molecules of type A are colliding with m molecules of type B (n plus m is the molecularity).

For gases the rate law can also be expressed in pressure units using e.g. the ideal gas law.

By combining the rate law with a mass balance for the system in which the reaction occurs, an expression for the rate of change in concentration can be derived. For a closed system with constant volume such an expression can look like

\frac{d[C]}{dt} = k(T)[A]^{n'}[B]^{m'}


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Temperature dependenceEach reaction rate coefficient k has a temperature dependency, which is usually given by the Arrhenius equation:

k = A e^{ - \frac{E_a}{RT} }

Ea is the activation energy and R is the gas constant. Since at temperature T the molecules have energies given by a Boltzmann distribution, one can expect the number of collisions with energy greater than Ea to be proportional to e^{\frac{-E_a}{RT}}. A is the pre-exponential factor or frequency factor.

The values for A and Ea are dependent on the reaction. There are also more complex equations possible, which describe temperature dependence of other rate constants which do not follow this pattern.

ExampleFor the reaction

2H_2 (g) + 2 NO(g) \rarr N_2 (g) + 2 H_2O (g)

The rate equation is:

r = k [H_2][NO]^2 \,

The rate equation does not simply reflect the reactants stoichiometric coefficients in the overall reaction: it is first order in H2, although the stoichiometric coefficient is 2 and it is second order in NO.

In chemical kinetics the overall reaction is usually proposed to occur through a number of elementary steps. Not all of these steps affect the rate of reaction; normally it is only the slowest elementary step that affect the reation rate. For example, in:

2 NO \ \overrightarrow\longleftarrow \ N_2O_2 (fast equilibrium)1.N_2O_2 + H_2 \rarr N_2O + H_2O (slow)2.N_2O + H_2 \rarr N_2 + H_2O (fast)3.

Reactions 1 and 3 are very rapid compared to the second, so it is the slowest reaction that is reflected in the rate equation. The slow step is considered the rate determining step. The orders of the rate equation are those from the rate determining step.

See alsoSteady state approximationCollision theory and transition state are chemical theories that attempt to predict and explain reaction rates.

Notes


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^ a b c IUPAC definition of rate of reaction (http://goldbook.iupac.org/R05156.html) 1.^ Kenneth Connors, Chemical Kinetics, 1990, VCH Publishers, pg. 142.

External linksChemical kinetics, reaction rate, and order (http://www.citycollegiate.com/chemical_kineticsXIa.htm) (needs flash player)The reaction of crystal violet with sodium hydroxide: a kinetic study(http://artsandscience.concordia.ca/facstaff/a-c/bird/c206/Labs/html/kinetics-lab-lbwks.html) .Reaction kinetics, examples of important rate laws (http://itl.chem.ufl.edu/4411/2041/lec_k.html) (lecture with audio).Rates of Reaction (http://www.chemguide.co.uk/physical/basicratesmenu.html#top)

Retrieved from "http://en.wikipedia.org/wiki/Reaction_rate"

Categories: Chemical kinetics | Physical chemistry | Chemical engineering

This page was last modified 10:35, 26 March 2007.All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.) Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a US-registered 501(c)(3)tax-deductible nonprofit charity.


Chapter 06

70 Chemistry

WHAT WE HAVE LEARNT

$ The valency of carbon is four.

$ Carbon forms covalent bonds in its compounds.

$ Carbon atom can form single bonded, double bonded and triplebonded compounds.

$ Carbon forms chain compounds and ring compounds.

$ Carbon atoms exhibit the property of 'catenation'.

$ Hydrocarbons are divided into 'alkanes, alkenes and alkynes'.

$ Different carbon compounds can have the same molecular formula.This phenomenon is called isomerism.

ORGANIC COMPOUNDS - NAMINGAND ISOMERISM6

71Standard 10

Organic compounds - naming and isomerism

NNNNNaming of Organic compounds

Examine the structural formulae of the twocompounds given below.

CH3 - CH2 - CH2 - CH3

CH3 - CH - CH3|CH3

Write down their molecular formulae. Arethey the same? Is there any difference in theirstructural formulae? What is the phenomenonof compounds having same molecular formulaeand different structural formula?

Each of these chain isomers, formed dueto the difference in the structure of the chains,is a different compound. Therefore they differin their names also.

Let us now examine how these compoundscan be named.

IUPAC has made certain rules for namingelements and compounds. This chapter dealswith the rules relating to the naming of organiccompounds.

Hydrocarbons

a. Unbranched alkanes

You know that uni, bi and tri indicate thenumbers 1, 2 and 3 respectively. Similarly someword roots are used to denote number of carbonatoms in the hydrocarbon. They are

C 1 - Meth C6 - Hex

C 2 - Eth C7 - Hept

C 3 - Prop C8 - Oct

ORGANIC COMPOUNDS - NAMING AND ISOMERISM

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Chapter 06

72 Chemistry

C 4 - But C9 - Non

C 5 - Pent C10 - Dec

1. Select the suitable word root basedon the number of carbon atoms in thechain.

2. By adding '-ane' to the word root ofthe saturated hydrocarbon, its namecan be derived.

For example, consider the following.

CH3 - CH2 - CH3

In this compound the number of carbonatoms is 3. Therefore the word root is 'prop'.Now add 'ane' to the word root and write thename.

prop + ane = propane

wordroot + ane = alkane

Now fill up table 6.1 given below.

Here there is a branch in the 2nd carbon.Such branched compounds may have more thanone carbon chain. Of these, the number of carbonatoms in the longest chain is taken as the basisfor writing the word root.

The word root of the above hydrocarboncan then be written as 'prop' and when '-ane' isadded you get its name.

The name of the group from the branchshould also be a part of the name. How manycarbon atoms are there in the branch? If there isone carbon then what should be the word root?'-meth', add -yl to it, to get 'methyl'. This maybe added as prefix to the name written above.The position number of the carbon atom in themain chain from which the branch arises shouldalso be written at the beginning of the name andput a '---' after this number.

2 - methylpropane

Table 6.1b. Branched alkanes

Write the IUPAC names of alkanes withupto 10 carbons. Try to write the name of thefollowing compound.

1 2 3

3 3CH C H C H− −|CH3

What is the difference between this hydrocarbon and those which we named earlier?

position of the branch + hyphen + theadjective denoting the branch + wordroot + suffix

Try writing the name of the followingcompound.

CH3 - CH2 - CH - CH2 - CH3 | CH2 | CH3

Compound Word rood Suffix Name

CH4 ............ ............ ............

CH3 - CH2 - CH2 - CH3 ............ ............ ............

......................................... ............ -ane ethane

CH3 - CH2 - CH2 - CH2 - CH3 ............ ............ ............

73Standard 10


Examine the compounds and their names in table 6.2 below.

I. 1CH3 - 2CH - 3CH2 - 4CH3 2 - methyl butane | CH3

II. 5CH3 - 4CH2 - 3CH2 - 2CH - 1CH3 2 - methyl pentane | CH3

III. 1CH3 - 2CH2 - 3CH - 4CH2 5CH3 3 - methyl pentane

| CH3

IV. 1CH3 - 2CH2 - 3CH - 4CH2 5CH3 3 - ethyl pentane

| CH2 CH3

V. 8CH3-7CH2-

6CH2-5CH2-

4CH-3CH2-2CH2-

1CH3 4 - propyl octane|CH2 - CH2 - CH3

Table 6.2

Consider the following examples.

I. 1CH3 - 2CH2 - 3CH2 - 4CH - 5CH3

| CH3

II. 5CH3 - 4CH2 - 3CH2 - 2CH - 1CH3

| CH3

I and II are the same compounds. Thelongest carbon chain has 5 carbon atoms. Sothe word root is 'pent' and the suffix is'-ane'. In compound I the methyl group isattached to the 4th carbon but in compound II,methyl group is attached to the 2nd carbon.While naming a compound as specified by theIUPAC, the branched carbon should be giventhe lowest number when counted from eitherends. Therefore the naming is done correctly inthe 2nd compound.

The compound is 2 - methylpentane.

Find the appropriate position number forthe carbon chains given below.

Ia. 1CH3 - 2CH2-

3CH -4CH2-5CH2-

6CH3|CH3

b. 6CH3 -5CH2-4CH-3CH2-

2CH2- 1CH3|CH3

IIa.1CH3 - 2CH2-

3CH2- 4CH2 - 5CH-6CH3

|CH3

b. 6CH3-5CH2-

4CH2-3CH2-

2CH-1CH3|CH3

Write the structural formula of the following:

a. 3 - ethylhexaneb. 4 - propylheptane

c. Hydrocarbon with more than onebranched carbon

When molecules with more than one branchin a single group is named, before the branchname, di, tri, tetra etc. were added to indicate 2,3, 4 etc. The numbers indicating position numbershould be separated by comma.

Chapter 06

74 Chemistry

Analyse table 6.3.

Compound Name

CH3 |

CH3 - C - CH3 2,2 - dimethylpropane |CH3

CH3 - CH - CH - CH3 2,3 - dimethylbutane | |

CH3 CH3

CH3 |

CH3 - CH2 - C - CH3 2,2 - dimethylbutane |CH3

CH3 - CH - CH - CH - CH3 2,3,4 - trimethylpentane | | |

CH3 CH3 CH3

Now write names of the following:

CH3|

CH3 - CH -C - CH3 ...................................................................| |CH3 CH3

CH3 |

CH3 - CH - C ----- CH - CH3 ................................................................... | | |CH3 CH3 CH3

Table 6.3

Table 6.4

Consider the structural formula of thefollowing:

33

3

6

12

5

2

4

32

3

4

2

53

1

6

CH CH | |

HC - HC - HC - HC - HC - HC

What will be the position number of carbonatom if we number from left to right? The sumof the position number of the carbon atom is2 + 4 = 6. If we number from right to left, thenthe sum of the position numbers is 3+5=8. Herewe will have to select that option where the sumof position numbers is less.

75Standard 10


i.e., the name of the compound is 2,4 - dimethylpentane.

In molecules having more than one branch,when the position numbers are different whencounting from right to left and left to right, findout the sum of position numbers. And select theone where the sum is less.

Complete table 6.5.

Naming of unsaturated hydrocarbons

a. Alkenes

While naming unsaturated hydrocarbonswith double bond, the longer chain with doublebond is taken as the basis. Add the suffix '-ene'to this. The position number of the double bondis shown before the word root. The positionwhich gives the smallest number for the carboncarbon double bond is to be chosen.

Compound Name

32223

323

CH - CH - CH - CH - CH - CH - CH| |

CH- CH CH

..................................................

......................................................... 5 - ethyl - 3,3 - dimethyl heptane

32223

3332

CH - CH - CH - CH - CH - C - CH - CH| | | CH CH CH-CH

......................................................................

Table 6.5

Now try to write the names of the chainisomers given below:

a. 3223 CH - CH - CH - CH

b.

33

3

CH - CH - CH| CH

c .

3

33

3

CH |

CH - C - CH| CH

Eg:1 2C H = C H2 2

Since there are 2 carbon atoms the wordroot is 'eth'. As there is a double bond '-ene'may be added. The IUPAC name ofCH2 -- CH2 is

eth + ene

→

ethene

Consider the following.

a. 1CH3 - 2CH = 3CH2 2- propene

b. 3CH3 - 2CH = 1CH2 1- propene

Observe how the names are written.

You can see that the two carbon chains arenamed in two different ways.

Chapter 06

76 Chemistry

Which way of naming is correct? Can

you explain why?

CH3 __ CH2

__ CH = CH __ CH3

What is the name of this compound?

2 - pentene or 3 - pentene? Justify your

answer.

Write down the names of the following:

CH3 __ CH2

__ CH = CH2

CH3 __ CH2

__ CH2 __ CH = CH

__ CH3

CH3 __ CH2

__ CH = CH __ CH2

__ CH3

CH2= CH __ CH2

__ CH3

b. Alkynes

While naming hydrocarbons with triple

bond after the word root '-yne' (alk + yne) is

added. The rules for naming double bonded

hydrocarbons are applicable to triple bonded

hydrocarbons also.

Write names of the following.

˛ ethyne

CHC2

CH3

CH ≡−−

3CHCC

3CH −≡−

3CH

2CHCC

2CH

3CH −−≡−−

II. Compounds with functionalgroups

a. Halogen compounds

Consider the compounds CH4, CH3Cl.

H C

H

H

H

H C

H

H

Cl

To get the name of the compound in which

the hydrogen atom of methane is substituted

by chlorine, add the prefix chloro - to the

word 'methane'. In general, to get the name

of compounds in which hydrogen atom of the

hydro carbon is substituted by a halogen, add

the prefix halo (halo- fluoro, chloro, bromo,

iodo).

Name the following compounds.

CH3 - CH2 - Cl

CH3 - CH2 - CH2 - Cl

CH3 - CH - CH3

| Cl

Can you explain why the chemical

properties of chloro methane is different from

that of methane.

The atoms or atom groups that get

substituted for the hydrogen atom in the

hydrocarbons determine the property of that

compound. These atoms or atom groups are

called functional groups.

The names of some compounds,

functional group, name of the functional group

and general name are given below in table 6.6.

77Standard 10


b. Alcohols

Consider the compound CH3- CH2- OH.How will you name the compounds with -OHas their functional group? For naming suchcompounds the following procedure can beadopted.

Consider the compound CH3- CH2- OH.Since there are 2 carbon atoms, the word rootcan be 'eth'. Since this is a saturatedhydrocarbon the prefix '-ane' should be addedand 'ol' is to be added to indicate the functionalgroup -OH. i.e., eth + ane -- e + ol → ethanol.

Alkane --- e + ol

→

Alkanol

Ethane --- e + ol

→

Ethanol

Name the following compounds.

a. CH3 - CH2 - CH2 - CH2 - OH

b. CH3OH

c. CH3-CH2-CH2-CH2-CH2-CH2-OH

c. Ether

Now we shall find out how to write thename of the following compounds.

CH3 - O - CH2 - CH3

The longest alkyl chain on either side ofoxygen should be considered for determiningthe word root. CH3 - O - CH2 - CH3, Herethere are two alkyl groups -CH3 and-CH2-CH3. The longest chain is the ethylgroup. Since it is a saturated hydrocarbon itcan be called ethane. The CH3 - O - group islinked to the ethyl group. The CH3- O - groupcan be named as meth + oxy = methoxy.

The IUPAC name of CH3 - O - CH2 - CH3is meth + oxy + ethane = methoxy ethane.

Now the compound

CH3 - CH2 - O - CH2 - CH2 - CH3 can beconsidered. The name of this compound isethoxy propane. Explain why this name isused.

Compound Functional Name of the Commongroup functional group name

CH3-CH2-OH -OH hydroxyl alcohol

CH3-CH2-COOH -COOH carboxyl acid

CH3-CO-CH3 -CO carbonyl ketones

CH3-CH2-CH2-CHO -CHO aldehyde aldehydes

CH3-O-CH3 - O - ether ether

CH3-CH2-NH2 -NH2 amino amines

CH3-CH2-CH2-NO2 -NO2 nitro nitro compound

Table 6.6

Chapter 06

78 Chemistry

Match properly the columns A and B in table 6.7 below.

Ethanol and dimethyl ether are examples

of functional group isomers. Now can you

write out a definition for functional group

isomerism?

From those given below find out functional

group isomers and note them in your science

diary.

CH3˛O ˛CH2˛CH3 CH3˛̨ CH2˛̨ CH2˛̨ OH

CH3 CH2 CH2 CH3 CH3 ˛̨ CH˛̨ CH3

| CH3

CH3COCH3 CH3CH2CHO

CH3

|CH3CH2CH2CH2CH3 CH3 - C - CH3

| CH3

A B

Methoxy propane CH3 ˛̨ CH2 ˛̨ CH2 ˛̨ CH2 ˛̨ O ˛̨ CH2 ˛̨ CH3

Ethoxy ethane CH3 ˛̨ O ˛̨ CH2 ˛̨ CH2 ˛̨ CH3

Ethoxy butane CH3 ˛̨ CH2 ˛̨ CH2 ˛̨ CH2 ˛̨ CH2 ˛̨ CH2 ˛̨ O ˛̨ CH3

Methoxy methane CH3 ˛̨ O ˛̨ CH2 ˛̨ CH3

Methoxy hexane CH3 ˛̨ CH2 ˛̨ CH2 ˛̨ CH3 ˛̨ CH3 ˛̨ O ˛̨ CH3

CH3 ˛̨ CH2 ˛̨ O ˛̨ CH2 ˛̨ CH3

CH3 ˛̨ O ˛̨ CH3

Table 6.7

Isomerism

You are familiar with compounds withsame molecular formula, but having differentstructural formula. Such compounds are calledisomers.

Based on the differences in the structures,isomers can be classified into various types.

a. Chain isomerism

Chain isomerism occurs due to thedifference in the carbon chain. Butane and2-methyl propane are examples.

b. Functional group isomerism

Find out the names of CH3-CH2-OH,CH3-O-CH3. Do they have the samemolecular formula and structural formula?

What is the functional group in the compoundsCH3-CH2-OH and CH3-O-CH3? Are they

the same?

79Standard 10


SUMMARY

$ Organic compounds are named according to the rules and

conventions formulated by IUPAC.

$ Compounds having the same molecular formula, but different

structural formulae are called isomers.

$ Isomers are of different types - chain isomers, functional group

isomers, position isomers, metamers etc.

c. Position isomerism

The following compounds are examples

of position isomerism.

4CH33CH2

2CH2 1CH2 OH : 1- butanol

OH |

1CH3 - 2CH - 3CH2 - 4CH3 : 2- butanol

Is there any difference in the carbon chain

structure, functional group and the position of

the functional groups?

Thus those isomers which differ in the

position of the functional groups in the same

carbon chain are termed as position isomers.

CH3__CH2

__CH2__CH2

__CH2__CH2

__CH2__OH

What is the name of this compound? Writeall the possible position isomers and their names.

d. Metamerism

Compare the two compounds.

CH3˛̨ CH2˛̨ O˛̨ CH2˛̨ CH3

CH3˛̨ O˛̨ CH2˛̨ CH2˛̨ CH3

Are the alkyl groups on either side of the

ether group and their molecular formula the

same? Here are some examples of

metamerism which arises due to the difference

in the number of carbon atoms in the alkyl

groups on either sides of a functional group.

CH3__ CH2

__ CH2 __ O __ CH2

__ CH2__ CH3

CH3 __ CH2

__ O__ CH2 __ CH2

__ CH2 __ CH3

CH3__ O __ CH2

__ CH2 __ CH2

__ CH2__ CH3

Write the names of the above compounds.

Chapter 06

80 Chemistry

1. Write the structure and name of the isomersof chloro propane (C3H7Cl).

2. Write a note on isomerism.

3. Write the IUPAC names of the following:

a. CH3 - CH - CH2 - CH2 - CH3 | CH3

b. CH3 |

CH3 - C - CH3 | CH3

c . OH |

CH3 - CH2 - CH - CH2 - CH3

d. CH3 - CH2 - CH - CH2 - CH2 - Cl | CH3

e . Cl Cl | |

CH3-CH2-CH-CH2-CH-CH2-CH-CH3 |Cl

f. CH3 - CH - CH - CH2-CH2-CH2- CH3| |CH3 CH2-CH3

g. CH3-CH2-CH=CH-CH2-CH2-CH2-CH3

4. Write the structures of the following

a . 2,2 - dimethylheptane

b. methylpropane

c . 3-ethyl - 2-methyl - 5-propylnonane

d. 2-ethyl - 3-methyloctane

e . 3-methyl - 1-butene.

5. Write the name of isomers of the followingcompounds and to which type ofisomerism is shown by them.

$ ethanol

$ methoxy ethane

$ 2 - chloro butane

$ 2 - propanol

$ 1 - propanol

$ 1 - butanol

$ ethoxyethane

$ 2-methyl - 1-chloropropane

$$$$$$

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