Carbon And Its Compound

COAL AND PETROLEUM

Firstly what is fuel ,fuel is a material that consist of energy stored in it. Most of the fuel are free carbons (coal , coke ,charcoal) or just carbon compounds (kerosene , LPG , petrol). When carbon in any form is burned in oxygen (of air) and forms carbon-di-oxide also releases heat and light. 

\[ C+O_{2}\longrightarrow{CO_{2}+Heat+light} \]

Although , Diamond and Graphite are also free carbon but we do not use them as a fuel.

Most of the fuels which we use today are obtained from coal , petroleum and natural gases. These fuel resources are also known as fossil fuels. Fossils are the remains of pre-historic plants and animals which are buried under earth , millions of years ago. Fossil fuels are formed by decomposition of remains of pre-historic plants which are buried under the earth long years ago .

 

HOW COALS ARE FORMED

Coals are formed by decomposition of large lands and large trees buried under millions of years ago because of natural disasters like volcanic eruption , earthquakes , and Tsunami etc the forest are buried under earth surface and as the time passes soil layers are increases. And under earth surface due to high pressure and high temperature and in the absence of air woods are converted into coal. 

 Coals are the complex mixture of carbon , hydrogen and oxygen some free carbons and small amount of nitrogen and sulphur compound are also present.

 

HOW PETROLEUM ARE FORMED

Petroleum is a dark colored , viscous and foul smelling crude oil. Petroleum derived from petra=rock and oleum=oil and called petroleum because it is trapped in the deapth of sea under earth crust in betweens rocks.

Crude oil petroleum is a complex mixture of several solid , liquid and gaseous hydrocarbons mixed with water, salt and earth particles.

Petroleum is not a single compound but a mixture of petrol , kerosene, LPG and diesel etc .

Petroleum (and natural gas ) is formed by the decomposition of  the remains of the extremely small plants and animals buried under sea , millions of years ago the plants and animals living in sea died and their body sank to the bottom of the sea and covered by mud and clay, under high pressure and heat they converted into fuel in the absence of oxygen.

NOTE : Since , coal and petroleum consist of small amount of nitrogen and sulphur and when we burn them oxides of nitrogen and sulphur which are pollutants.

 

FLAMES

All gaseous fuels are burn with flame but only solid and liquid fuels which first vaporise and then burn with flame.

Types of flame

1.When oxygen supply is sufficient in burning of fuel then blue flame is produced. Blue flame does not gives out much light that’s why called non-luminous flame.Generally they are saturated carbon compound.

2.When oxygen supply is insufficient in burning of fuel then yellow flame is produced. Yellow flame does not gives out much light that’s why called non-luminous flame. (the reason behind yellow light is unburnt hot carbons) . Generally they are unsaturated carbon compound.

 

CHEMICAL PROPERTIES OF CARBON

 

1.COMBUSTION (OR BURNING) The process of burning carbon compounds in air to give carbon-di-oxide , heat , water and light. Alkane is an excellent fuel because it produces lot of heat on burning in air. Example : LPG (​\( C_{4}H_{10} \)​)

\[ C_{4}H_{10}+2O_{2}\longrightarrow{CO_{2}+2H_{2}O+Heat+light} \]

 

2.Subsitution Reactions : The reaction in which atoms, ions or groups are replaced by another atom , ion, or group called as subsitution reaction. Subsitution reaction is the characteristic reaction of alkanes. Example : Halogenation.

\[ \begin{matrix}CH_{4}\\{methane}\end{matrix}{+}\begin{matrix}Cl_{2}\\{chlorine}\end{matrix}\xrightarrow{sunlight}\begin{matrix}CH_{3}Cl\\{Chloromethane}\end{matrix}+\begin{matrix}HCl\\{Hydrogenchloride}\end{matrix} \]

 

3.Additive Reaction : is the characteristic reaction of unsaturated hydrocarbons or multiple bonded compounds after the addition reaction unsaturation of the compound decreases and saturation of compound increases. Example : 

Addition reaction of ethene with hydrogen 

\[ \begin{matrix}CH_{2}=CH_{2}\\{ethene}\end{matrix}{+}\begin{matrix}H_{2}\\{hydrogen}\end{matrix}\xrightarrow[heat]{Ni~catalyst}\begin{matrix}CH_{3}-CH_{3}\\{ethane}\end{matrix} \]

The addition of hydrogen to an unsaturated hydrocarbon to obtain a saturated hydrocarbon is called hydrogenation.

 

ETHANOL (OR ETHYL ALCOHOL)  ​

\( C_{2}H_{5}-OH \)​or ​\( CH_{3}-CH_{2}-OH \)

 

CHEMICAL PROPERTIES 

1.Combustion: Ethanol is a highly inflammable liquid. It catches fire easily and starts burning. Ethanol readily in air to form carbon-dioxide , heat , light and water.

\[ \begin{matrix}C_{2}H_{5}OH\\Ethanol\end{matrix}+3O_{2}\xrightarrow[burning]{combustion}\begin{matrix}2CO_{2}\\carbon~dioxide\end{matrix}+\begin{matrix}3H_{2}O\\water~vapour\end{matrix}+Heat+Light \]

 

2.Oxidation: Oxidation means controlled combustion. When ethanol is heated with alkaline potassium permanganate solution (or acidified potassium dichromate solution), it gets oxidised to ethanoic acid.

\[ \begin{matrix}C_{2}H_{5}OH\\Ethanol\end{matrix}+\begin{matrix}2[O]\\Nascent~oxygen\end{matrix}\xrightarrow[or~acidified~k_{2}Cr_{2}O_{7}]{Alkaline~KMnO_{4};Heat}\begin{matrix}CH_{3}COOH\\Ethanoic~acid\end{matrix}+\begin{matrix}H_{2}O\\water~vapour\end{matrix} \]

 

3.Reaction with Sodium Metal: Ethanol reacts with sodium to form sodium ethoxide and hydrogen gas.

\[ \begin{matrix}2C_{2}H_{5}OH\\Ethanol\end{matrix}+\begin{matrix}2Na\\Sodium\end{matrix}\longrightarrow\begin{matrix}2C_{2}H_{5}O-Na\\Sodium~ethoxide\end{matrix}+\begin{matrix}H_{2}\\hydrogen\end{matrix} \]

This reaction is used as test for ethanol.

 

4.Dehydration: Dehydration means removal of water molecules from it. When ethanol is heated with excess of concentrated sulphuric acid at 170°C (443K) it get dehydrated to form ethene.

\[ \begin{matrix}CH_{3}-CH_{2}OH\\Ethanol\end{matrix}\xrightarrow[(Dehydration)]{Conc.H_{2}SO_{4}~170°C}\begin{matrix}CH_{2}=CH_{2}\\Ethene\end{matrix}+\begin{matrix}2H_{2}O\\Water\end{matrix} \]

In above reaction sulphuric acid is a dehydrating agent.

 

5.Reaction with Ethanoic acid (to form ester) : Ethanol reacts with ethanoic acid on warming in the presence of a few drops of concentrated sulphuric acid to form a sweet smelling ester.

\[ \begin{matrix}CH_{3}COOH\\Ethanoic~acid\end{matrix}+\begin{matrix}C_{2}H_{5}OH\\Ethanol\end{matrix}\xrightarrow{Conc.H2SO_{4}}\begin{matrix}CH_{3}COOC_{2}H_{5}\\Ethyl~Ethanoate\\or~Ethyl~acetate\\(sweet~smelling~ester)\end{matrix}+H_2O \]

The reaction in which a carboxylic acid combines with an alcohol to form an ester is called esterification.

 

PHYSICAL PROPERTIES

Ethanol is a colourless liquid having a pleasant smell and a burning taste.

Ethanol is a volatile liquid having a low boiling point 78°C (351 K).

Ethanol is soluble in water due to presence of hydroxyl group.

Ethanol is a covalent compound.

Ethanol do not have any effect on litmus paper (neutral compound.)

 

ETHANOIC ACID (OR ACETIC ACID)

\[ CH_{3}COOH \]

 

PHYSICAL PROPERTIES

1. Ethanoic acid is a colourless liquid having a sour taste and a smell of vinegar.

2. The boiling point of ethanoic acid is 118°C (391 K).

3.When pure ethanoic acid is cooled , it freezes to form a colourless, ice-like solid (which look like a glacier). Due to this , pure ethanoic acid is called glacial ethanoic acid (or glacial acetic acid.)

4. Ethanoic acid is soluble in water in all proportion.

 

CHEMICAL PROPERTIES 

1. Action on litmus: Ethanoic acid is an acid , being an acid it turns blue litmus to red.

 

 

 

SOAPS AND DETERGENT

Any substance which has cleaning action in water is called a detergent.

There are two types of detergent are :

1. Soapy detergents (also called soaps)

2. Non-Soapy detergents (also called synthetic detergents)

 

SOAPS

A soap is a sodium salt (or potassium salt ) of a long chain carboxylic acid (fatty acid) which has cleansing properties in water. Soap has large number of chain of non ionic hydrocarbon group and an ionic group ​\( COO-Na^{+} \)​.

Examples of soaps are :

(i) Sodium Stearate ​\( C_{17}H_{15}COO-Na^{+} \)​ is a sodium salt of long chain of saturated fatty acid called stearic acid \( C_{17}H_{15}COOH \)

They have long alkyl group \( C_{17}H_{15} \)and ionic carboxylic group \(COO-Na^{+} \) .

(ii) Sodium palmitate ​\( C_{15}H_{37}COO-Na^{+} \)​ is a sodium salt of long chain of saturated fatty acid called palmitic acid ​\( C_{15}H_{37}COOH \)

This soap is the salt of strong base (sodium hydroxide) and a weak acid (carboxylic acid) , so a solution of soap in water is basic in nature and being basic it turns red litmus to blue.

 

MANUFACTURING OF SOAP

Soap is made from animal fat or vegetable oils . Fat and oils are naturally occurring esters of higher fatty acid (long chain carboxylic acid ) and an alcohol called glycerol. And when these fats and oil is heated with concentrated sodium hydroxide solution (caustic soda solution) they form soap and glycerol.

\[ \begin{matrix}Fat~or~oil\\(an ~ester)\end{matrix}+\begin{matrix}NaOH\\sodium~hydroxide\\(alkali)\end{matrix}\xrightarrow{Heat}\begin{matrix}Soap\\(sodium~salt~of\\fatty~acid)\end{matrix}+\begin{matrix}Glycerol\\(an ~alcohol)\end{matrix} \]

Above reaction is an example of saponification. The process of making soap by hydrolysis of fats and oils with alkalis is called saponification.

Or we can say that the process of splitting of fats or oil to form soap is called saponification.

 

Why common salt (NaCL) is added in making of soap from soap mixture.

Because common salt decreases the solubility of soap present in soap mixture due to which all soap separate out .

 

STRUCTURE OF SOAP MOLECULES

Soap is mainly made up of two parts 

(i) long chain of hydrocarbon 

(ii) A short ionic part containing ​\( -COO-Na^{+} \)

And they together called tadpole structure. Long hydrocarbon chain is hydrophobic (water repelling) in nature due to this they are insoluble in water but soluble in oil and grease. Where as ionic part(is hydrophilic) is soluble in water but insoluble in oil and grease . Mostly dirt is a form of oil and grease and hydrocarbon part is soluble in oil and grease due to this it attaches to the dirt particles (oil and grease) and ionic part attaches to water molecules in which soap solution in dissolved and dirty clothes is dipped.

And together hydrocarbons and ionic part form a micelle. A micelle is a spherical aggregate of soap molecules in the soap solution in water is called a micelle. And these micelle are big enough to make solution colloidal.

 

CLEANSING ACTION OF SOAP

When soap is dissolve in water , it forms a colloidal suspension in water in which soap molecules cluster together to form a spherical micelles . And in a soap micelle the soap molecules are arranged radially with hydrocarbon end directed towards the center (at the dirt) where as ionic part is directed outwards (because negative charge at the ends repel each other) . The micelle formation takes place only when soap is added to water. When the dirty clothes dipped in soap solution , the dirt present in clothes is surrounded by micelles and hydrocarbon part attach with dirt and this dirt is removed by rinsing dirty clothes in clean water number of times.

[NOTE : Soap does not work in organic solvents like ethanol ]

 

LIMITATIONS OF SOAP

1. When soap is used for washing clothes with hard water , a large amount  of soap is wasted in reacting with the calcium and magnesium ion of hard water to form an insoluble precipitate called scum , before it can be used for the real purpose of washing. So, a large amount of soap is needed for washing clothes when the water is hard.

2. The scum (or curdy precipitate) formed by the action of hard water on soap , sticks to the clothes being washed and interferes with the cleaning ability of the additional soap. This makes the cleaning of clothes difficult. The formation of lather or foam is necessary for removing dirt form clothes during the washing of clothes. Soap does not give lather easily with hard water because it first reacts with calcium and magniseum ions present in the hard water to form insoluble precipitates of calcium and magnesium salt of fatty acids . Soft water however does not contains calcium and magnesium ions and therefore , lathers are easily formed when soap is added. Example distilled water is the softest water we have.

 

DETERGENTS

Detergents are also called “soap-less-soaps” because though they act like a soap in having the cleansing properties , they do not contain the usual soaps like sodium stearate etc. 

A detergent is a sodium salt of a long chain benzene sulphonic acid (or the sodium salt of a long chain alkyl hydrogensulphate ) which has cleansing properties in water. A detergent have a large number of non-ionic hydrocarbons and an ionic group like sulphonate group ​\( SO_{3}^{-}Na^{+} \)​ and sulphate group ​\( SO_{4}^{-}Na^{+} \)​ .

Some example of detergents are given below :

\[ \begin{matrix}CH_{3}-(CH_{2})_{11}-C_{6}H_{4}-SO_{3}^{-}Na^{+}\\Sodium~n-dodecyl~benzene~sulphonate\\(common~detergent)\end{matrix} \]

\[ \begin{matrix}CH_{3}-(CH_{2})_{10}-CH_{2}-SO_{4}^{-}Na^{+}\\Sodium~n-dodecyl~sulphate\\(common~detergent)\end{matrix} \]

Structure of detergents are similar to that of soaps.(long chain of hydrocarbons and short ionic part)

Also cleansing action of detergents are also similar to that of a soap.

 

DETERGENTS HAVE NUMBER OF ADVANTAGES OVER SOAP 

1.Detergents can be used with hard water as well as soft water but soaps only used in soft water.

2. Detergents have stronger cleansing action than that of soaps.

3. Detergents are more soluble than soaps in water.

 

An important disadvantage of detergents over soap is that ,some of detergents are not biodegradable ,that is they can not be decomposed by micro-organism like bacteria and hence results in water pollution.

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