Chemistry The Building Block of The World

Monday 3 September 2018

Lesson 7: Organic Chemistry

Under this topic we will look at the homologous series one after the other, I mean the alkane, alkene, alkyne and so on. One after the other, there method of production, physical and chemical properties, test and uses.

INTRODUCTION

What is organic chemistry?

This is the branch of chemistry that deals with the compound of hydrocarbons.

Types of organic compounds

There are two major types of hydrocarbon which are

1. Aliphatic hydrocarbon: these are the hydrocarbon that are made up of straight, branched or cyclic carbon atoms.

2. Aromatic hydrocarbon : these are the hydrocarbon that contains ring structure of carbon with Non- localized orbital. i.e. non-localized pi bond e.g. benzene, phenol, toluene and turpentine.

Aliphatic hydrocarbon carbon grouped into:

a. Acyclic hydrocarbon: these are hydrocarbon with straight chain e.g. ALKANE and ALKENE

b. Cyclic hydrocarbons: these are hydrocarbons in cyclic form. e.g. Cyclo-pentane, Cyclo-hexane. They only form ring structures with single bond.

Acyclic can be group as saturated and unsaturated hydrocarbons

a. Saturated hydrocarbons: these are hydrocarbons with single covalent bond e.g. the ALKANE family.

b. Unsaturated hydrocarbons: these are hydrocarbons with double or triple covalent bond. E.g. ALKENES and ALKYNES.

CHEMISTRY OF ALKANE

Alkanes are saturated, acyclic, aliphatic hydrocarbon with the general formula CnH2n+2. Where is an integer starting from 1.the functional group of alkane is (C-C).

THE FIRST TEN MEMBER OF THE FAMILY ARE:

Number of carbon	Name	Molecular Formula
1	Methane	CH₄
2	Ethane	C₂H₆
3	Propane	C₃H₈
4	Butane	C₄H₁₀
5	Pentane	C₅H₁₂
6	Hexane	C₆H₁₄
7	Heptane	C₇H₁₆
8	Octane	C₈H₁₈
9	Nonane	C₉H₂₀
10	Decane	C₁₀H₂₂

MOLECULAR STRUCTURE

Name	Molecular Formula	Condensed structure
Methane	CH₄	CH4
Ethane	C₂H₆	CH3-CH3
Propane	C₃H₈	CH3-CH2-CH3
Butane	C₄H₁₀	CH3-CH2-CH2-CH3
Pentane	C₅H₁₂	CH3-CH2-CH2-CH2-CH3
Hexane	C₆H₁₄	CH3-CH2-CH2-CH2-CH2-CH3
Heptane	C₇H₁₆	CH3-CH2-CH2-CH2-CH2-CH2-CH3
Octane	C₈H₁₈	CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Nonane	C₉H₂₀	CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Decane	C₁₀H₂₂	CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

General Laboratory preparation alkane

Alkane are generally prepared in the laboratory by heating the mixture of Alkanoate (salt made from Alkanoic acid and sodium metal like sodiumthanoate, sodiumpropanoate, sodiumbutanoate. E.t.c.) salt with soda lime (CaHNaO₂).

GENERAL PHYSICAL PROPERTIES OF ALKANE

1. Methane and ethane are gas at room temperature, propane and butane are liquid at room temperature while others are solid

2. They have no action on litmus paper

3. They are slightly soluble in water. Solubility decreases as the the number of carbon atom increases.

GENERAL CHEMICAL PROPERTIES

1. Combustion reaction: all alkane burns in air with a blue non-luminous flame to give carbon(iv)oxide and water. E.g. CH₄ + 2O₂→ CO₂ + 2H₂O

2. Substitution reaction: substitution reaction is a kind of chemical reaction whereby an atom or a group of atom is replace by another atom of group of atom. Alkanes can undergo substitution reaction with the halogens. And the reaction is also called halogenation. For example methane undergoes substitution reaction with chlorine to give choloro-methane in the presence of sunlight.

Chemical test for alkane

1. All members of alkane has no effect on bromine water

2. All members of alkane has no effect on acidified and alkalined potassium heptaoxodichromate(vi). (K₂Cr₂O₇) and potassium tetraoxomanganates (vii).(KMnO₄).

USES OF ALKANES

1. They can be used as fuel

2. Methane is used in the production of water gas

3. They can be used in the production of hydrogen, alkynes, chloroform and so on.

4. Tetrachloromethane is used as organic solvent in industries for manufacturing process.

Monday 19 December 2016

Organic Chemistry