L-4 Carbon and its compounds Covalent Bond: The chemical bond formed by the sharing of electrons between two atoms is known as covalent bond The sharing of electrons takes place in such a way that each atom in the resulting molecule gets the stable electron configuration of inert gases. Whenever a non metal combines with another non metal sharing of electrons takes place between their atoms. The bond formed between the atoms of the same element is a covalent bond. The shared electrons are counted with both the atoms due to which each atom in the resulting molecules gets an inert gas electron arrangement of either 8 electrons or 2 electrons in the outermost shell. Types of covalent bond : i. Single covalent bond ii. Double covalent bond iii. Triple covalent bond i. Single covalent bond Single covalent bond or single bond is formed by the sharing of one pair of electrons between two atoms. A single covalent bond is denoted by putting a short line (-) between two atoms.

Formation of Hydrogen Molecule Hydrogen atom has only one electron in its outermost shell, and requires one more to acquire the nearest noble gas configuration of helium (He: 1s2).

To do so, two hydrogen atoms contribute one electron each to share one pair of electrons between them. This leads to the formation of a single covalent bond between the two hydrogen atoms.

Formation of Chlorine Molecule

Chlorine atom has seven valence electrons. Thus, each Cl atom requires one more electron to acquire the nearest noble gas configuration (Ar:2, 8, 8). They do this by mutual sharing of one pair of electrons as shown below.

Formation of Methane (CH4)

Carbon atom has four electrons in its outermost shell. Thus, it requires four more electrons to acquire a stable noble gas configuration. Each hydrogen atom has only one electron in its outermost shell and requires one more electron to complete its outermost shell (to acquire He configuration). This is done as follows:

Formation of ethane – C2H6

2. Double covalent bond Double covalent bond is formed by the sharing of two pairs of electrons between two atoms. A double covalent bond is denoted by putting 2 short line (=) between two atoms. Formation of CO2 : Formation of O2

Formation of C2H4 Electronic configuration of C = K L 2 4 Electronic configuration of H = K 1 3. Triple covalent bond : Triple covalent bond is denoted by putting 3 short lines ( ) between the two atoms. Eg: a. Formation of N2 : Electronic configuration of N = K L 2 5

b. Formation of ethyne ( C2H2) ; Electronic configuration of C = K L 2 4 Electronic configuration of H = K 1 Properties of covalent compounds : 1. Covalent compounds are usually liquids and gases . only a few of them are solids. Solid covalent compounds

i. Iodine ii. Glucose iii.Naphthalene iv.Camphor Liquid covalent compounds i. Methane ii. Propane 2. They usually have low melting and low boiling points. 3. They are insoluble in water but they are soluble in organic solvents. 4. They do not conduct electricity Carbon compounds : Carbon is an element (a non metal). It belongs to 2nd period, 14th group of the periodic table. Carbon derived its name from the Latin word carbo means coal. Atomic number of carbon is 6

Electronic configuration is K L 2 4 hence carbon is tetravalent. Availability of Carbon in earth’s crust is 0.02% in the form of minerals like CO3 an HCO3. Availability of carbon in the atmosphere is 0.03% in the form of CO2 More than 5 million carbon compounds are known to chemists Carbon has four electrons in its outermost shell and needs to gain or lose 4 electrons to attain noble gas configuration. If it were to gain or loose electrons i. It could gain 4 electrons to form C4- anion but it would be difficult for the nucleus with 6 protons to hold on to 10 electrons. ii. It could loose 4 electrons forming C4+ cation but it would requires a large amount of energy to remove 4 electrons leaving behind a carbon cation with 6 protons in its nucleus holding on to 2 electrons. Carbon overcomes this problem by sharing its electrons with other atoms of carbon or with atoms of other elements. Versatile nature or unique nature of carbon : Carbon shows unique properties like tetravalency, catenation, formation of multiple bonds and most of its compounds form isomers. Catenation : The property of self linking of carbon atom through covalent bonds in order to form straight or branched chains and rings of different sizes is known as catenation. Eg:

Carbon atom poses the property of catenation to a greater extent than any other element. Tetravalency of Carbon : Carbon has four electrons, it can neither loose nor gain electrons to attain octet, it forms covalent bonds by sharing its 4 electrons with other carbon atoms or atoms of other elements. “The characteristic property of carbon atom by virtue of which it form four covalent bonds is called tetravalency of carbon atom.” Carbon form compounds with oxygen, hydrogen, nitrogen, sulphur, halogens and many other elements. Carbon forms very strong bonds with most other elements making these compounds exceptionally stable. The reason for the formation of strong bonds by carbon is its small size. This enables the nucleus of the carbon atom to hold on to the shared pair of electrons strongly. Tendency to form multiple bonds : Due to small size, carbon atom forms double or triple bonds. As a result It can form variety of compounds. Isomerism: The organic compounds having same molecular formula but different structural formulae are called isomers and the phenomenon is isomerism. Organic compounds with minimum 4 carbon atoms show the phenomena isomerism

Hydrocarbons : A compound made up of hydrogen and carbon only is called hydrocarbon E.g. Methane CH4 Ethane C2H6 Ethene C2H4 Ethyne C2H2 The carbon atoms are arranged in hydrocarbons in straight chain, branched chain or ringed structures.

Aliphatic hydrocarbons : The hydrocarbons in which carbon atoms are arranged in straight or branched chains are called aliphatic hydrocarbons Aliphatic hydrocarbons are of two types:

a. saturated aliphatic hydrocarbons b. Unsaturated aliphatic hydrocarbons.

Hydrocarbons

Cyclic hydrocarbons

Unsaturated

Alkeness Alkynes

Alicyclic Aromatic

Aliphatic hydrocarbons

Saturated

Alkane

Saturated hydrocarbons (Alkanes) A hydrocarbon in which the carbon atoms are connected by only single bonds is called saturated hydrocarbons. Saturated hydrocarbons are called alkanes and are also called paraffins Param - Little Affin - Affinity Eg : Methane ,CH4 , Ethane ; C2H6 Propane : C3H8 Condensed structure : CH3CH2CH3 Butane : C4H10 Condensed structure CH3CH2CH2CH3 The general formula of alkanes is CnH2n+2 The saturated hydrocarbons are chemically not reactive

Unsaturated hydrocarbons Hydrocarbons in which the two carbon atoms are connected by a double bond or a triple bond then these hydrocarbons are called unsaturated hydrocarbons Alkenes: An unsaturated hydrocarbon in which the two carbon atoms are connected by a double bond is called alkene. Eg: Ethene C2H4 : Propene C3H6 Condensed formula : CH3CH=CH2 Butene C4H8 Structural formula : Condensed formula : CH3 CH2 CHCH2 Alkenes contain –C=C-- group

The general form of alkene is CnH2n. Alkenes are also called olefins. Since an alkene has double bond between two carbon atoms, simplest alkene

will have two carbon atom in its molecule. There can be no alkene having only one carbon atom.

ii. Alkynes : An unsaturated hydrocarbon in which two carbon atoms are connected by a triple bond is called an alkyne. Eg: Ethyne C2H2 Propyne C3H4 Butyne C4H6 An alkyne contains –C C – graph. General form of alkyne CnH2n-2 Unsaturated hydrocarbons (Alkenes, Alkynes) are more reactive than saturated hydrocarbons (Alkanes) Alkyl group: The group formed by the removal of one hydrogen atom from an alkane molecule is called an alkyl group Eg: CH4 Methyl group C2H6 Ethyl group C3H8 Propyl group

The alkyl groups are denoted by R. The general formula of alkyl group is CnH2n+1 One valancy of carbon atom is free in an alkyl group Write the structure, electron dot structure, formula of ethane, ehene, ethyne i. Ethane C2H6

ii. Ethene C2H4 iii. Ethyne C2H2 b.Cyclic hydrocarbons : The hydrocarbons in which the carbon atoms are arranged in form of closed chains or rings. The cyclic hydrocarbons may be saturated or unsaturated. They are classified as Alicyclic hydrocarbons Aromatic hydrocarbons

Alicyclic hydrocarbons : These hydrocarbons contain a ring chain of three or more carbon atoms. This cyclic compounds are named by prefixing “cyclo” before the name of the corresponding straight chain hydrocarbon i. Saturated Cyclo propane Cyclo Butane CycloPentane Cyclohexane

Unsaturated e.g.: Cyclopropene cyclobutene

cyclopentene cylcohexene Cyclobutyne Aromatic Hydrocarbons: The hydrocarbons contain at least benzene ring in their molecules. The benzene ring is a specific type of ring structure of six carbon atoms having C-C single bond and C=C double bond in alternate positions.

Toluene Phenol Naphthalene

Hetero atoms: The atom replacing the hydrogen atom in an organic compound is called hetero in an organic compound is called hetero atoms. These hetero atoms give characteristic properties to compounds regardless the length and nature of carbon atom. Functional group : A functional group be defined as an atom or group of atoms which determine the properties of organic compounds.

The functional group is the site of chemical reactivity in the organic molecule

Homologous series : A series of organic compounds having similar structures and similar chemical properties in which the successive members differ in their molecular formula by CH2 group. The different members of the series are called homologous Eg: An alkane family represents a homologous series. All the alkanes have similar structure with the single covalent bond and show similar chemical properties. Each successive members differ by a CH2 group Methane –CH4 Ethane - C2H6 Propane –C3H8 Butane – C4H10 Similarly alkene and alkyne family also represent homologous series. Alkene Alkyne Ethane - C2H6 Ethyne – C2H2 Propane – C3H8 Propyne - C3H4 Butane – C4H10 Butyne – C4H6 Homologous series of alcohol is as follows CH3OH C2H5OH C3H7OH Characteristics of homologous series :

1. All the members of homologous series can be represented by the same general formula

Alkane – CnH2n+2 Alkene – CnH2n Alkyne – Cnh2n-2

Alcohol – R – OH

2. Any two adjacent homologous differ by a-CH2 group.

3. The difference in the molecular masses of any two adjacent members is 14u

4. All the members of homologous series have similar chemical properties due to

similar structural formula.

5. The members of a homologous series show a gradual change in their physical properties such as melting points, boiling points, density, solubility etc. on going from higher to lower molecular series

Simple rules for nomenclature of organic compounds :

How to name organic compounds using the IUPAC rules

In order to name organic compounds you must first memorize a few basic names. These names are listed within the discussion of naming alkanes. In general, the base part of the name reflects the number of carbons in what you have assigned to be the parent chain. The suffix of the name reflects the type(s) of functional group(s) present on (or within) the parent chain. Other groups which are attached to the parent chain are called substituents.

Alkanes - saturated hydrocarbons The names of the straight chain saturated hydrocarbons for up to a 12 carbon chain are shown below. The names of the substituents formed by the removal of one hydrogen from the end of the chain is obtained by changing the suffix -ane to -yl.

Number of Carbons Name

1 methane

2 ethane

3 propane

4 butane

5 pentane

6 hexane

7 heptane

8 octane

9 nonane

10 decane

11 undecane

12 dodecane

There are a few common branched substituents which you should memorize. These are shown below.

Here is a simple list of rules to follow. Some examples are given at the end of the list.

1. Identify the longest carbon chain. This chain is called the parent chain.

2. Identify all of the substituents (groups appending from the parent chain).

3. Number the carbons of the parent chain from the end that gives the substituents the lowest numbers. When compairing a series of numbers, the series that is the "lowest" is the one which contains the lowest number at the occasion of the first difference. If two or more side chains are in equivalent positions, assign the lowest number to the one which will come first in the name.

4. If the same substituent occurs more than once, the location of each point on which the substituent occurs is given. In addition, the number of times the substituent group occurs is indicated by a prefix (di, tri, tetra, etc.).

5. If there are two or more different substituents they are listed in alphabetical order using the base name (ignore the prefixes). The only prefix which is used when putting the substituents in alphabetical order is iso as in isopropyl or isobutyl. The prefixes sec- and tert- are not used in determining alphabetical order except when compared with each other.

6. If chains of equal length are competing for selection as the parent chain, then the choice goes in series to: a) the chain which has the greatest number of side chains. b) the chain whose substituents have the lowest- numbers. c) the chain having the greatest number of carbon atoms in the smaller side chain. d)the chain having the least branched side chains.

7. A cyclic (ring) hydrocarbon is designated by the prefix cyclo- which appears directly in front of the base name.

In summary, the name of the compound is written out with the substituents in alphabetical order followed by the base name (derived from the number of carbons in the parent chain). Commas are used between numbers and

dashes are used between letters and numbers. There are no spaces in the name.

Here are some examples:

Alkyl halides The halogen is treated as a substituent on an alkane chain. The halo- substituent is considered of equal rank with an alkyl substituent in the numbering of the parent chain. The halogens are represented as follows:

F fluoro-

Cl chloro-

Br bromo-

I iodo-

Here are some examples:

Alkenes and Alkynes - unsaturated hydrocarbons

Double bonds in hydrocarbons are indicated by replacing the suffix -ane with -ene. If there is more than one double bond, the suffix is expanded to include a prefix that indicates the number of double bonds present (-adiene, -atriene, etc.). Triple bonds are named in a similar way using the

suffix -yne. The position of the multiple bond(s) within the parent chain is(are) indicated by placing the number(s) of the first carbon of the multiple bond(s) directly in front of the base name.

Here is an important list of rules to follow:

1. The parent chain is numbered so that the multiple bonds have the lowest numbers (double and triple bonds have priority over alkyl and halo substituents).

2. When both double and triple bonds are present, numbers as low as possible are given to double and triple bonds even though this may at times give "-yne" a lower number than "-ene". When there is a choice in numbering, the double bonds are given the lowest numbers.

3. When both double and triple bonds are present, the -en suffix follows the parent chain directly and the -yne suffix follows the -en suffix (notice that the e is left off, -en instead of -ene). The location of the double bond(s) is(are) indicated before the parent name as before, and the location of the triple bond(s) is(are) indicated between the -en and -yne suffixes. See below for examples.

4. For a branched unsaturated acyclic hydrocarbon, the parent chain is the longest carbon chain that contains the maximum number of double and triple bonds. If there are two or more chains competing for selection as the parent chain (chain with the most multiple bonds), the choice goes to (1) the chain with the greatest number of carbon atoms, (2) the # of carbon atoms being equal, the chain containing the maximum number of double bonds.

5. If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Alcohols Alcohols are named by replacing the suffix -ane with -anol. If there is more than one hydroxyl group (-OH), the suffix is expanded to include a prefix that indicates the number of hydroxyl groups present (-anediol, -anetriol, etc.). The position of the hydroxyl group(s) on the parent chain is(are) indicated by placing the number(s) corresponding to the location(s) on the parent chain directly in front of the base name (same as alkenes).

Here is an important list of rules to follow:

1. The hydroxyl group takes precedence over alkyl groups and halogen substituents, as well as double bonds, in the numbering of the parent chain.

2. When both double bonds and hydroxyl groups are present, the -en suffix follows the parent chain directly and the -ol suffix follows the -en suffix (notice that the e is left off, -en instead of -ene). The location of the double bond(s) is(are) indicated before the parent name as before, and the location of the hydroxyl group(s) is(are) indicated between the -en and -ol suffixes. See below for examples. Again, the hydroxyl gets priority in the numbering of the parent chain.

3. If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Ethers You are only expected to know how to name ethers by their commmon names. The two alkyl groups attached to the oxygen are put in alphabetical order with spaces between the names and they are followed by the word ether. The prefix di- is used if both alkyl groups are the same.

Here are some examples:

Aldehydes Aldehydes are named by replacing the suffix -ane with -anal. If there is more than one -CHO group, the suffix is expanded to include a prefix that indicates the number of -CHO groups present (-anedial - there should not be more than 2 of these groups on the parent chain as they must occur at the ends). It is not necessary to indicate the position of the -CHO group because this group will be at the end of the parent chain and its carbon is automatically assigned as C-1.

Here is an important list of rules to follow:

1. The carbonyl group takes precedence over alkyl groups and halogen substituents, as well as double bonds, in the numbering of the parent chain.

2. When both double bonds and carbonyl groups are present, the -en suffix follows the parent chain directly and the -al suffix follows the -en suffix (notice that the e is left off, -en instead of -ene). The location of the double bond(s) is(are) indicated before the parent name as before, and the -al suffix follows the -en suffix directly. Remember it is not necessary to specify the location of the carbonyl group because it will automatically be carbon #1. See below for examples. Again, the carbonyl gets priority in the numbering of the parent chain.

3. There are a couple of common names which are acceptable as IUPAC names. They are shown in the examples at the end of this list but at this point these names will not be accepted by the computer. Eventually they will be accepted.

4. If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Ketones Ketones are named by replacing the suffix -ane with -anone. If there is more than one carbonyl group (C=O), the suffix is expanded to include a prefix that indicates the number of carbonyl groups present (-anedione, -anetrione, etc.). The position of the carbonyl group(s) on the parent chain is(are) indicated by placing the number(s) corresponding to the location(s) on the parent chain directly in front of the base name (same as alkenes).

Here is an important list of rules to follow:

1. The carbonyl group takes precedence over alkyl groups and halogen substituents, as well as double bonds, in the numbering of the parent chain.

2. When both double bonds and carbonyl groups are present, the -en suffix follows the parent chain directly and the -one suffix follows the -en suffix (notice that the e is left off, -en instead of -ene). The location of the double bond(s) is(are) indicated before the parent name as before, and the location of the carbonyl group(s) is(are) indicated between the -en and -one suffixes. See below for examples. Again, the carbonyl gets priority in the numbering of the parent chain.

3. If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Carboxylic Acids Carboxylic acids are named by counting the number of carbons in the longest continuous chain including the carboxyl group and by replacing the suffix -ane of the corresponding alkane with -anoic acid. If there are two -COOH groups, the suffix is expanded to include a prefix that indicates the number of -COOH groups present (-anedioic acid - there should not be more than 2 of these groups on the parent chain as they must occur at the ends). It is not necessary to indicate the position of the -COOH group because this group will be at the end of the parent chain and its carbon is automatically assigned as C-1.

Here is an important list of rules to follow:

1. The carboxyl group takes precedence over alkyl groups and halogen substituents, as well as double bonds, in the numbering of the parent chain.

2. If the carboxyl group is attached to a ring the parent ring is named and the suffix -carboxylic acid is added.

3. When both double bonds and carboxyl groups are present, the -en suffix follows the parent chain directly and the -oic acid suffix follows the -en suffix (notice that the e is left off, -en instead of -ene). The location of the double bond(s) is(are) indicated before the parent name as before, and the -oic acid suffix follows the -en suffix directly. Remember it is not necessary to specify the location of the carboxyl group because it will automatically be carbon #1. See below for examples. Again, the carboxyl gets priority in the numbering of the parent chain.

4. There are several common names which are acceptable as IUPAC names. They are shown in the examples at the end of this list but at this point these names will not be accepted by the computer. Eventually they will be accepted.

5. If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Here are some examples:

Esters Systematic names of esters are based on the name of the corresponding carboxylic acid. Remember esters look like this:

The alkyl group is named like a substituent using the -yl ending. This is followed by a space. The acyl portion of the name (what is left over) is named by replacing the -ic acid suffix of the corresponding carboxylic acid with -ate.

Here are some examples:

Amines You are only expected to know how to name amines by their common names . They are named like ethers, the alkyl (R) groups attached to the nitrogen are put in alphabetical order with no spaces between the names and these are followed by the word amine. The prefixes di- and tri- are used if two or three of the alkyl groups are the same. NOTE: Some books put spaces between the parts of the name, but we will not. Follow the examples.

Here are some examples:

Summary of functional groups

Functional group Prefix Suffix

carboxylic acids none -oic acid

aldehydes none -al

ketones none -one

alchols hydroxy- -ol

amines amino- -amine

ethers alkoxy- -ether

fluorine fluoro- none

chlorine chloro- none

bromine bromo- none

iodine iodo- none

Rule – 1 Selection of carbon Choose the longest carbon chain. The compound is then named as the derivative of the alkane which corresponds to the longest chain. Rule 2 The branched chains are considered to be substituents and their positions are indicated by the number of carbon atoms to which they are attached. Rule 3 The carbon atoms of the longest chain are numbered in such a way that the substituents get the smallest possible number

Rule 4 In case any functional group is present in the chain the carbon atoms are numbered in such a way that the functional group gets the smallest possible number. Rule 5 In case of different substituents are attached to the chain they are arranged and named alphabetically. Rule 6

The positions of alkyl groups are indicated by writing the position and name of the alkyl group just before the name of the parent carbon Rule 7 Multiple alkyl groups are labeled with greek numerical prefixes such as di for 2, tri for 3, tetra for 4, penta for 5

Chemical properties of carbon compounds: 1. Combustion or burning: The process of burning a carbon compound in air to give CO2 , Water vapour, heat and light is known as combustion. Combustion is also called burning. E.g.: CH4 + 2O2 CO2 + 2H20 + Heat + Light C2H4 + 3O2 2CO2 + 2H2O + Heat + light CH3CH2OH + 3O2 2CO2 + 3H2o + Heat + Light Note : The major constituent of LPG is butane The major constituent of CNG is methane The saturated hydrocarbon generally burns with a blue non-sooty flame because the percentage of carbon in the saturated hydrocarbons is comparatively low which gets oxidized completely by the oxygen present in air The unsaturated hydrocarbon (alkenes, alkynes) burn in air with a yellow sooty flame because the percentage of carbon in unsaturated hydrocarbon is comparatively high which does not get oxidized completely in air. A mixture of acetylene and air is not used for welding because burning of acetylene in air produces a sooty flame which is not hot enough to melt metals for welding. If a mixture of acetylene and pure oxygen is burned then acetylene burns completely producing a blue flame and the oxy acetylene flame is extremely hot and produces very high temperature which is used for welding metals. Disadvantages of incomplete combustion:

In complete combustion of fuels leads to un burnt carbon in the form of soot which pollutes the atmosphere.

The incomplete combustion of fuel leads to the formation of extremely poisonous gas CO.

Incomplete combustion produces less heat than that produced by complete

combustion.

Fuels such as coal, petroleum, etc have some amount of nitrogen and sulphur in them. On heating they are converted into their oxides ( NO , SO2 ) which are released in the atmosphere,. These are major pollutants.

2.Oxidation Oxidation is the process in which oxygen is added to the substance. Oxidation is a controlled combustion. Oxidation of carbon compounds gives different products. Eg: Ethanol on treatment with alkaline KMnO4 or acidified K2Cr2O7 gives ethanoic acid.

CH3CH2OH 4alkalineKMnO CH3COOH + H2O

(ethanol) (ethanoic acid) On treatment with alkaline KMnO4 solution ethene is oxidized to ethylene glycol. Ethyne on treatment with alkaline KMnO4 give oxalic acid

3. Substitution reaction It is a characteristic property of alkanes. The reaction in which an atom or group of atoms in a molecule is replaced by different atoms or group of atoms is called substitution reactions. Saturated hydrocarbons in presence of sunlight reacts with halogens. Eg:

CH4 + Cl2 Sunlight

CH3Cl + HCl (Chloromethane)

CH3Cl + Cl2 Sunlight

CH2Cl2 + HCl (diChloromethane)

CH2Cl2 + Cl2 Sunlight

CHCl3 + HCl (triChloromethane)

CHCl3 + Cl2 Sunlight

CCl4 + HCl (tetraChloromethane) 4. Addition reaction: The reaction in which an unsaturated hydrocarbon combines with another substance to give a single product is called addition reaction It is the characteristic property of unsaturated hydrocarbons. Eg: Halogens add on to ehene at room temperature to form addition compound.

Eg: Addition of hydrogen Hydrogen reacts with ethene in the presence of finely divided Nickel at 473 K to form ethane Hydrogenation : The addition of hydrogen to an unsaturated hydrocarbon to obtain a saturated hydrocarbon is called hydrogenation. The process of hydrogenation has an important industrial application. It is used to prepare vegetable ghee from vegetable oil. Hydrogenation of oil Vegetable oils like groundnut oil, cotton seed oil, mustard oil which are liquids at room temperature are unsaturated fats having double bonds and triple bonds between some of their atoms. When a vegetable oil is heated with hydrogen in the presence of finely divided nickel as catalyst then a saturated fat is called vegetable ghee is formed . This reaction is called hydrogenation of oil. Vegetable oils containing unsaturated fatty acids are good for health.

Test for unsaturated compounds: When bromine water is added to an unsaturated compound the red brown colour of bromine water is discharged. So if an organic compound decolourises bromine water it will be an unsaturated compound otherwise it is a saturated hydrocarbon Ethanol Ethanol is the second and most important member of alcohol series Chemical formula – C2H5OH or CH3CH2OH Its common name is ethyl alcohol. The structural formula is It is a constituent of alcoholic beverages such as beer, wine, whisky and cough syrups and digestive syrups etc Physical properties 1. Ethanol is a colourless liquid having pleasant smell and burning taste. 2. It has a boiling point of 78oC and 351 K. 3. It is miscible in water in all proportions. Note: The solubility of ethanol in water is due to the presence of hydroxyl groups. 4. Ethanol has no effect on any litmus solution. It is a neutral compound. Absolute alcohol : 100 % pure ethanol is called absolute alcohol. Rectified spirit Ethanol containing 5% water is called rectified spirit. The rectified spirit is the commercial alcohol

Chemical properties: Ethanol is highly inflammable liquid and burns with oxygen with a pale blue oxygen flame to produce CO2, H2O (vapour and a lot of heat and light) C2H5OH + 3O2 2CO2 + 3H2O + Heat + Light Ethanol is used as a additive in petrol 2. Reaction with Na metal: Ethanol reacts with Na metal to form sodiumethoxide and H2 gas is liberated. 2CH3CH2OH + 2Na 2CH3CH2ONa + H2 This reaction is used as a test for alcohol. Activity: Take about 2ml of pure alcohol in a test tube and add a small piece of clean sodium metal to it, rapid effervescence due to the evolution of hydrogen gas is produced. When a burning splinter is brought near the mouth of the test tube the gas burns with a pop sound which is a characteristic of hydrogen gas. 3. Oxidation: When ethanol is heated with alkaline KMnO4 or acidified K2Cr2O7 it gets oxidized to CH3COOH (ethanoic acid)

CH3CH2OH + 2(O) 4alkalineKMnO CH3COOH + H2O

Ethanol gets oxidized to ethanol with chromic anhydride.

C2H5OH 2 33

Cr O inCH COOH CH3CHO

4. Action with concentrated H2SO4 (dehydration) Ethanol reacts with conc.H2SO4 at 443 K to produce unsaturated hydrocarbon ethene. This reaction is known as acidic dehydration of ethanol

The con. H2SO4 is call dehydrating agent. 5. Reaction with ethanoic acid (esterification) Ethanol reacts with ethanoic acid on warming in the presence of con. H2SO4 to form a sweet smelling ester called ethylethanoate

C2H5OH + CH3COOH 2 4ConH SO CH3COOC2H5 + H2O

The reaction in which a carboxylic acid combines with an alcohol in the presences of con H2SO4 to form an ester is called esterification. Activity:

1. Take 1 ml of ethanol and 1ml of glacial acetic acid along with a few drops of concentrated H2SO4 in a test tube.

2. Warm in a water bath for at least 5 minutes 3. Pour the contents of test tube into a beaker containing 20 to 50 ml of water and

smell the resulting mixture. 4. A sweet smell is obtained indicating the formation of odour.

Tests for alcohol: Sodium metal test Add a small piece of Na metal to the organic liquid to be tested taken in a test tube. If bubbles of H2 gas are produced it indicates that given organic liquid is a alcohol Ester formation test Warm the organic compound to be tested with a glacial acetic acid and few drops of con. H2SO4. A sweet smell due to formation of ester indicates the presence of alcohol Denatured alcohol: It is 95% ethanol which is made unfit for drinking purpose by adding small quantities of poisonous substances like methanol, pyridine, copper sulphate etc., Power alcohol: It is a mixture of 20% ethanol and 50% gasoline and a solvent such as benzene, ether, etc., It is a substitute for gasoline

ETHANOIC ACID

Ethanoic acid is the second member of homologous series of carboxylic acid. Its chemical formula is CH3COOH. Structural formula is Its common name is acetic acid. 5 to 8% solution of ethanoic acid in water is called vinegar. Vinegar is widely used as a preservative in pickles. The melting point of pure ethanoic acid is 290 K and hence it often freezes in cold climates. Due to this pure ethanoic acid is called glacial ethanoic acid or glacial acetic acid. Physical Properties: 1. Ethanoic acid is colourless, corrosive liquid with sharp pungent odour of vinegar 2. It has a sour taste. 3. Its boiling point is 319 K (1180C) 4. It is miscible with water, ether, alcohol in all proportions. Chemical properties: 1. Action on litmus Being acidic in nature ethanoic acid turns blue litmus solution red. Dilute ethanoic acid turns universal indicator orange showing that its pH is about 4. 2. Reaction with metals: It reacts with metals such as Na, K, Mg, Al, etc to form metal ethanoate and liberate H2 gas 2CH3COOH + 2Na 2CH3COONa + H2 (g) (Sodium ethanoate)

3. Reaction with carbonate : When sodium carbonate is added to a solution of acetic acid brisk effervescence of CO2 is evolved 2CH3COOH + Na2CO3 2CH3COONa + CO2 + H2O 4. Reaction with bicarbonate: Ethanoic acid reacts with sodium hydrogen carbonate to evolve brisk effervescence of CO2 gas 2CH3COOH + NaHCO3 2CH3COONa + CO2 + H2O 5. Reaction with an alkali: Ethanoic acid reacts with alkalis to form salt and water. 2CH3COOH + NaOH 2CH3COONa + H2O 6. Reaction with alcohol: (Esterification) Ethanoic acid reacts with alcohols in the presence of concentrated H2SO4 to form esters which have very pleasant odour

2CH3COOH + C2H5OH 2 4ConcH SO 2CH3COOC2H5 + H2O

(ethyl ethanoate) 7.Saponification The alkaline hydrolysis of ester to give sodium salt of carboxylic acid and alcohol is called saponification.

CH3COOC2H 5 + NaOH 2CH3COONa + C2H5OH

Tests for ethanoic acid

1. Litmus test 2. Sodium bicarbonate test 3. Ester test

Uses of ethanoic acid:

1. Dilute ethanoic acid in the form of vinegar is used as food preservative in the preparation of pickles and sauces.

2. Ethanoic acid is used in preparation of dyes, plastics, pharmaceuticals

3. It is used in the manufacture of rubber and silk.

Classify the following compounds as alkanes, alkenes, alkynes. Write their IUPAC name and common name 1. C2H2 - Alkyne - Ethyne acetylene 2. C2H6 – Alkane - Ethane 3. C2H4 – Alkene - Ethene – Ethylene 4 C3H8 - Alkane - propane 5. C3H4 – Alkyne - propyne Name the compound CH3 | 1. CH3 – C – CH2 – CH3 2- Methyl butane Write the structural formulae of two types of butane (C4H10). Write their common names and IUPAC names

Write the structural formula of isomers of pentane and write IUPAC names: Write the structural formula of isomers of hexane and write IUPAC names : Soaps and Detergents : Any substance which has cleaning action in water is called detergent. There are two types of detergents.

Soapy detergent Soap less / non-soapy detergents.

Soapy detergents are called soaps. Non soapy detergents are called synthetic detergents or detergents. Soaps: Soap is the sodium/potassium salt of long chain fatty acids(carboxylic acid) which has cleansing properties in water Eg:- Sodium stearate soap ( C17H35COONa) It is the sodium salt of long chain saturated fatty acid called stearic acid Sodium Oleate soap (C17H33COONa)

It is the sodium salt of long chain unsaturated fatty acid called oleic acid. Sodium palmitate soap (C15H31COONa) It is the sodium salt of long chain saturated fatty acid called palmetic acid. Soap is the salt of strong base NaOH and weak acid. So a soap solution is basic in nature and turns red litmus to blue. Soap is manufactured by heating animal fat or vegetable oil with concentrated NaOH solution. The fats or oils react with NaOH to form soap and alcohol.

Fat/Vegetable oil + NaOH Heat Soap + Alcohol

The process of making soap by the hydrolysis of fats and oils with alkali is called saponification. Structure of a soap molecule: A soap molecule is made up of two parts

1. A long chain hydrocarbon

2. A short ionic part containing - COO -Na+

For simplicity soaps and detergents may be represented as above. The soap molecule is said to have tad pole structure.

The long hydrocarbon chain is hydrophobic (water repellent). So the hydrocarbon part of soap molecule is insolvent in water but soluble in oil and grease. The ionic portion of soap molecule is hydrophilic (water attractant). So the ionic portion of soap molecule is soluble in water. Cleansing action of soap: The dirt in the cloth is oily in nature. When the dirty cloth is dipped in soap or detergent solution, the soap and dirt particles come in contact with each other. The non-polar tails of soap begin to dissolve in non-polar oil and grease while the ionic end of soap remains directed in water . The soap molecules thus form structures called micelles where one end of the soap molecule is towards the oil droplet while the ionic end faces outside. As more and more soap molecules enter the grease each fat or oil particle is surrounded by a number of negatively charged ends. Since the like charges repel each other the oil or grease droplets break off into small globules of oil . These are still surrounded by the negatively charged polar heads of the soap molecule. This prevents the small globules from coming together to form bigger particles. The rubbing by hand or mechanical stirring also helps to break the grease particles. In this manner the grease particles can completely broken up and it forms emulsion of grease or oil contained in dirt. As a result the cloth gets free from dirt and droplets are washed away with water.

Limitations of Soap : 1. Soap is not suitable for washing clothes with hard water because of the following Reasons:

i. Hard water contains salts of Ca & Mg. When soap is added to hard water, Ca and Mg ions of hard water react with soap forming insoluble calcium and magnesium slats of fatty acids.

2C17H35COONa + MgCl2 (C17H35COO)2Mg + 2NaCl 2C17H35COONa + CaCl2 (C17H35COO)2Ca + 2NaCl

ii. When hard water is used soap forms insoluble precipitates of Ca, Mg salts which sticks to the cloth being washed. Therefore it interferes with the cleaning ability of the soap and makes the cleaning process difficult.

Detergents : Detergents are also called soap less soaps because they do not contain usual soap like sodium stearate etc., Detergents are better cleaning agents than soaps because they do not form insoluble Ca & Mg salts with hard water and hence can be used. It is not possible to check whether a sample of water is hard by using detergent because a detergent gives a lather easily in hard water. A detergent is a sodium salt of long chain benzene sulphonic acid. Or Sodium salt of long chain alkyl hydrogen sulphate, which have cleansing properties in water O | CH3(CH2)11 - C6H4 - S – O – Na + | O (Sodium n – dodecyl Benzene sulphonate) CH3 – (CH2)10 – CH2 – So4

– Na + (sodium n do decyl sulphate)

Soap

1. Soaps are Na or K salts of long chain fatty acids, The ionic groups in the soap is –COO-

Na+ 2. They cannot be used in acidic solution 3. They cannot be used in hard water as they produce precipitate with Ca2+ and Mg2+ ions 4. Soaps are biodegradable. So they do not cause any pollution.

Detergent

1. detergents are Na salts of long Chain benzene sulphnate or alkyl sulphonate The ionic group is –SO3

– Na + or –SO3

– Na +

2. They can be used in acidic solution 3. They can be used even in hard water as they do not form precipitate with Ca2+ or Mg2+ ions 4. some of the detergents are not biodegradable they pollute reiver and lake water.

Disadvantages of detergents over soaps:

1. Some of the detergents which are made from large chain hydrocarbons having a lot of branched chains are not biodegradable i.e they cannot be decomposed by micro bacteria and thus cause pollution in rivers and lakes.

To solve this problem, now a days the detergents are prepared from hydrocarbons having minimum branching. These are degraded more easily than branched chain detergents.

Advantages of detergents over soap: 1. Synthetic detergents can be used for washing even in hard water whereas soaps are not suitable to use with hard water. 2. Synthetic detergents can be used even in acidic solution because they do not decompose in acidic solution. On the other hand soaps cannot be used in acidic medium because they are decomposed into the carboxylic acid. 3. Synthetic detergents are more soluble in water than soaps. 4. Synthetic detergents have a strong cleansing action than soaps

Name the following compound CH3 | 1. CH3 – C – CH3 2,2 dimethyl alkyl butane | C2H6 CH3 | 2. CH3 – CH = CH – C – CH3 | CH3 Write the structural formula of the following 1. 2 methyl 2 butane 2. 2methyl propene 3. CH3CH2-COOH Propanoic acid 4. CH3CHO ethanol 5. CH3CH2CH2OH Propanol 6. CH3 – CH – CH3 2Chloro propane | Cl 7. CH3 CH – CH3 propane- 2- ol | OH 8. Butanoic acid 9. Methanol 10 CH3- C – CH3 2 Methyl propene | CH2 11 2,2 – dimethyl propane (neo pentane) 12 Cyclo propane

1. A compound has molecular formula C3H6. One mole of X reacts with one mole of bromine to yield a compound Y. Deduce structures of X and Y 2. Define Isomerism. Wirte down the structures and names of isomers of butane 3. Which of the following belongs to same homologous series. Why? C3H8, C3H6, C4H8, C4H6 4. Which of the following compounds would give addition reaction / i. C2H6, ii. C3H8 , iii C3H6, iv. C2H2, V CH4, vi C3H4 5. What happens when vetable oil is hydrogenated? Explain with equation. 6. Write down the structure of i. Ethanoic acid ii. Butanol 7. What happens when a mixture of sodium ethonate and soda lime is heated 8. Give the names of the following functional groups CHO CO OH COOH 9. Write chemical equations for reaction of ethanoic acit with i. Na2CO3 ii. K iii soda lime iv Ehanol in presence of Con.H2SO4 10. An organic compound ‘A’ of molecular formula C2H6O, on oxidation gives an acid B with same number of carbon atoms in the molecule as A. Compound A is often used for sterlisation of skin by doctors. Name the compound A and B. Write the chemical equation.

11. What is meant by functional group in an organic compound ? 12 Give the structural formula of the functional groups in i. Acetic acid ii. Ethyl alcohol 13. Write the molecular formula of ethanol and propionic acid (common name of propanoic aci) H H H | | | 14. The structural formula of an ester is H – C – O – C – C – C - H | | | | | O H H H Of acid and alcohol from which it is formed Acid Alcohol 15. An organic compound A has formula C2H4O2 reacts with Na metal and evolves a gas B which readily catches fire. ‘A’ also reacts with ethanol in the presecnce of Con. H2SO4 to form sweet smelling substance used in perfumes. i. Identify A,B,C. ii. Write balanced chemical equation to represent the conversion of A into C 16. Distinguish between addition and substitution 17. Compare the following properties of ethanol and ethanoic acid I. Litmus test ii. Sodium bicarbonate test iii. Na metal test

18. An organic compound A is widely used as preservatives inpickle and has a formula C2H4O2. The compound reacts with ethanol to form a sweet smelling compound B i. Identify A ii. Write the chemical equation iii. How can we get compound A from B iv. which gas is produced when compound A reacts with washing soda. 19. Why does carbon form largest number of compounds 20. why are some of these called saturated and the other unsaturated 21. Which of these two are more reactive 22. Write the name of the compound i. CH3CH2Br ii. H H H | | | C – C – C – C C – H pentyne | | | H H H 23. An organic compound burns with soothy yellow flame. It is saturated or unsaturated 24. Two carbon compound A and B have C3H8 and C3H6 respectively as their molecular formula. Which one of tw is most likely to show addition reaction. Justify your answer 25. Explain with the help of chemical equation how addition reaction is useful in vegetable ghee industry/ 26. Why does carbon form compound mainly by covalent bonding ? 27 List any two reasons for carbon forming a very large No. of compounds. 28,. An organic compound X is a liquid which often freezes during winter in cold county’s having formula C2H4O2. On warming with ethanol in presence of few drops of con. H2SO4 a compound Y with sweet smell is formed. Identify X and Y