Properties of carbon compounds:
- Carbon compounds has low melting and boiling point as compared to the ionic compounds because the forces of attraction between the molecules are not strong like in ionic compounds.
- As carbon compounds are non conductors of electricity that means they does not give any types of ions.
- Carbon atom has 4 electrons in its outermost shell and hence to complete its octet it needs again 4 electrons so that it gets noble gas configuration.
- The bonds which are formed by the sharing of an electron pairs between two atoms are called as covalent bonds.
- The molecule formed by the covalent bonds are having strong bonding within the molecule. But they have weak interatomic forces.
- And hence carbon compounds or covalently bonded compounds has very low melting and boiling point.
- and boiling point.
For example:
- H2 molecule is formed due to the sharing of pair of electrons and forms covalent bond.
- Oxygen atom also has 6 electrons in its outermost shell. So, to complete its octet it shares it’s two electrons with another oxygen atom and forms the O2 molecule with covalent bonding as shown in figure below.
- Also, nitrogen atom has 5 electrons is its outermost shell and hence it shares 3 electrons with another nitrogen atom by forming the covalent bond and forms the N2 molecule as shown in figure below.
- As we know that, carbon atom has 4 electrons in its outermost shell so it shares it’s 4 electrons with other 4 hydrogen atom and thereby complete its octet and forms the CH4 molecule as shown figure below.
- All these 4 C-H bonds formed are the covalent bonds.
Versatile nature of carbon:
- The ability of carbon atom to form covalent bond makes it to form large number of carbon compounds.
- Carbon can form large number of covalent compounds because of the following reasons.
1.)
- Carbon has unique ability to form the bonds with another carbon atoms also. And such property is named as catenation.
- By catenation long chains of carbon, branched chains of carbon or carbon atoms forming ring are formed.
- And main thing is that carbon atom bonds with other carbon atom by single bond, double bond or sometimes with triple bond also.
- Saturated compounds are those compounds in which there is single bond between two carbon atoms exist.
- And unsaturated compounds are those in which there is double or triple bonds are possible between two carbon atoms.
- And the carbon -carbon bond formed is very strong and hence it must be stable.
2.)
- As the valency of carbon atom is 4, so it forms 4 covalent bonds with other monovalent atoms.
- And hence carbon forms compounds with oxygen, hydrogen, nitrogen, Sulphur, chlorine and many more atoms.
- Due to the small size of carbon atom, it forms the stable compounds also.
Saturated and unsaturated carbon compounds:
- Methane CH4 is the compound formed between hydrogen and carbon atom.
- Also, ethane C2H6 is the saturated carbon compound which has 1 C-C bond and 6 C-H bonds as shown in figure below.
- Next saturated carbon compound is the propane having molecular formula as C3H8 and having structural formula as shown in figure below.
- Anothercompound of carbon and hydrogen is C2H4 called as ethene.
- In ethene there is double bond is formed between two carbon atoms as shown in figure below.
- Hence ethene is the unsaturated carbon compound.
Chains, Branches and rings:
- Following are the saturated compounds of the carbon with their molecular and structural formula. And all these are the long chain saturated compounds of carbon.
- If we have taken butane having molecular formula C4H10. Then we can draw two structural formulae for butane with single molecular formula as given below.
- So, these are the branched chain saturated compounds of carbon.
- The compounds having identical molecular formula but different structural formula is called as structural isomers.
- If we have taken hexane C6H12 then it can be drawn in the form of ring also as shown in figure below. And it is the cyclohexane which is saturated ring compound of carbon.
- Benzene having molecular formula C6Hs has the structure as shown below which is called as unsaturated cyclic compounds of carbon.
- Carbon atom forms bonding with other elements like halogens, nitrogen, oxygen and sulphur also.
- According to the functional group which is present in the compounds they are named differently. Some compounds and their functional groups are as given below.
Nomenclature of the carbon compounds:
The names of the carbon compounds are given by using some rules which are discussed below.
1.) First, we have to identify the number of carbon atoms in the compounds. If three carbon atoms are there that means propane is there.
2.) If any functional group is present in the compound, then we have to name it with prefix or suffix.
3.) If in the compound ketone group is present then we have to remove e from propane and have to add one.
So, name formed is propanone.
4.) If there is unsaturated carbon compound is present then we have to replace ane by ene or yne.
From the following table we can understand more easily the nomenclature of carbon compounds.
Chemical properties of carbon compounds:
1.) Combustion:
- Carbon and its allotropic forms react with oxygen and get burned to form carbon dioxide and releases heat and light also.
- Following are the reaction which shows oxidation of carbon compounds.
C + O2 —–> CO2 + heat and light
CH4 + O2 ——> CO2 + H2O + heat and light
CH3CH2OH + O2 ——-> CO2 + H2O + heat and light
- When saturated compounds of carbon burns give clear flame while when unsaturated carbon compound burns give yellow flame with black smoke also.
2.) Oxidation:
- We know that carbon compounds get easily oxidised on combustion.
- When alcohols on oxidation in the presence of alkaline KMnO4 or acidic K2Cr2O7 and on heating gives acetic acid as shown in the following chemical reaction.
CH3-CH2-OH ———-> CH3COOH
- Here, potassium permanganate or acidified potassium dichromate acts as oxidizing agents.
3.) Addition reaction:
- When unsaturated hydrocarbons get added with hydrogens in the presence of palladium or nickel forms the saturated carbon compound.
- Following reaction shows the how unsaturated hydrocarbons are converted into saturated hydrocarbons.
- This type of reaction is mainly used in hydrogenation of vegetable oil. Since vegetable oils are long unsaturated carbon chains while animal fats are having saturated carbon chains.
4.) Substitution reaction:
- In the presence of sunlight chlorine gets added to hydrocarbons and it’s a very fast reaction.
- And the reaction occurs is as shown below.
CH4 + Cl2 ——> CH3Cl + HCl
Some important carbon compounds:
Ethanol:
Properties of ethanol:
- Ethanol is the alcohol and which is the active ingredient of all the alcoholic drinks.
- Due to its good solvent property, it is also used in medicines like tincture iodine, cough syrups and in many tonics also.
- It is soluble in water and causes drunkenness.
- Also, long duration of consumption of alcohols like ethanol may cause health issues.
Reactions of ethanol:
1.) Alcohols reacts with sodium and evolves hydrogen gas.
And when ethanol reacts with sodium it forms sodium ethoxide as given in the following chemical reaction.
2Na + 2CH3CH2OH ——> 2CH3CH2ONa + H2
2.) Ethanol on heating at 443K temperature with excess concentrated sulphuric acid (Hot conce. H2SO4) undergoes dehydration and forms ethene as given in the following chemical reaction.
CH3-CH2-OH ———> CH2=CH2 + H2O
Ethanoic acid:
Properties of ethanoic acid:
- Ethanoic acid is the carboxylic acid which is also named as acetic acid.
- Vinegar which is the 5-8% solution of acetic acid in water used as preservatives in pickles.
- As the freezing point of acetic acid is 290K and hence it freezes during winter or in cold climates also. Due to which it is also named as glacial acetic acid.
Reactions of ethanoic acid:
1.)
- When acids and alcohols react then there will be formation of esters.
- Ethanoic acid reacts with absolute ethanol in the presence of acid and forms ester as given below.
- Esters are sweet to smell and they are mostly used in making perfumes and flavouring agents also.
- Esters on reaction with sodium hydroxide then they get converted into alcohols and sodium at of carboxylic acids.
- This reaction is called as saponification because it is used in making soaps.
- Since soaps are the sodium or potassium salts of long chain carboxylic Acids.
CH3COOC2H5 ——–> C2H5OH + CH3COONa
2.) Ethanoic acid reacts with sodium hydroxide and gives salt named as sodium acetate and water.
NaOH + CH3COOH ——> CH3COONa + H2O
3.) Ethanoic acid reacts with carbonates and hydrocarbonates and forms the salt, CO2 and water.
The salt formed here is the sodium acetate.
2CH3COOH + Na2CO3 ——> 2CH3COONa + H2O + CO2
CH3COOH + NaHCO3 ——> CH3COONa + H2O + CO2
Soaps and detergents:
- The soap molecules are the salts of potassium or sodium long chain carboxylic acid.
- The ionic end of soap reacts with water and carbon chain reacts with oil. And hence they form the structure called as micelles which forms emulsion in the water. This soap micelles helps in pulling dirt in water wash our cloths cleanly.
- Soap causes the hardness of water and it is overcome by using detergents as cleansing agent.
- Detergents are the sodium salts of sulphonic acids or ammonium salts with chloride or bromide ions.
- Thus, detergents are effective in hard water also. They are used mainly to make shampoos and products for cleansing cloths.
- The action of soaps and detergents is based on the which hydrophobic and hydrophilic group is present in the molecule which helps to emulsify the oily dirt and removes it to make cloths clean.