Element Elements and Compounds Hydrocarbons Mineral Coal and Mineral Oil Compounds A compound is a...

ElementElements and Compounds HydrocarbonsMineral Coal and Mineral

Oil

Compounds

A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.

Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.

Objectives:Hydrocarbons – Alkanes, Alkenes and Alkynes.

Preparation and Properties of Methane, Ethene and Ethyne.

ElementElements and Compounds Extraction of SulphurNon-metals

Compounds



Mineral Coal and Mineral Oil PetroleumHydrocarbons

Hydrocarbons

Hydrocarbons are substances that contain Hydrogen and Carbon only.

Hydrocarbons are divided into a series of families or groups called Homologous Series.

A homologous series is a group of compound which have a general formula and are chemically similar.


Compounds




AlkanesThe Alkanes have a general formula of CnH2n+2

They run from C1 –C60 approx.C1-C4 are gasesC5-C17 are liquidsC17-C60 are Waxy Solids

As we progress between successive members of the series we find that there is a difference of CH2 in their formulae. As a direct result there is a regular increase in their Boiling Points since more energy is required to break up the longer chains.

All Alkanes are flammable, have a pH of 7 and are insoluble in water.


Compounds




The Alkane members


Compounds




Methane

Methane gas is the chief constituent in Marsh gas available from the mines of mineral coal and gas collected over petroleum in the sedimentary rocks in the crust of the earth.


Compounds




Preparation of MethaneMethane gas is obtained by heating sodium acetate and soda lime (3:1 proportion mixture of sodium hydroxide and calcium oxide).


Compounds




Properties of Methane

It bums with blue flame when burnt in air and gives carbon dioxide and water.

At room temperature and standard pressure, methane is a colourless, odourless gas. It is insoluble in water and is lighter than air.


Compounds




Alkenes

The Alkenes are homologues series with general formula CnH2n.The first member of the alkene series is Ethene.

An alkene is an unsaturated chemical compound containing at least one carbon-to-carbon double bond.

The simplest alkenes, ethene, propene and butene are gases. Linear alkenes of approximately five to sixteen carbons are liquids, and higher alkenes are waxy solids.

Alkenes are relatively stable compounds, but are more reactive than alkanes due to the presence of a carbon-carbon pi-bond.


Compounds




The Alkene members


Compounds



PetroleumMineral Coal and Mineral

Oil Hydrocarbons

Ethene (Ethylene)

Ethene is a hydrocarbon with the formula C2H4 or H2C=CH2.

Ethene is also an important natural plant hormone, used in agriculture to force the ripening of fruits.


Compounds




Oil Hydrocarbons

Preparation of Ethene Ethane gas can be prepared in a laboratory by the cracking of

hydrocarbons such as kerosene or candle wax.

Ethane gas is collected in the gas jar by downward displacement of water.


Compounds




Oil Hydrocarbons

Ethene removes the pink colour of dilute alkaline solution of potassium permanganate (KMnO4) and makes it colourless. This reaction indicates the property or unsaturation of ethene.

Ethene gas is insoluble in water. It is colourless and odourless gas. It is lighter than water.

Properties of Ethene


Compounds




Oil Hydrocarbons

Reaction of ethene with hydrogen:

Reaction of ethene with halogens:

Properties of Ethene

Polymerisation:


Compounds




Oil Hydrocarbons

Alkynes

Alkynes are hydrocarbons that have a triple bond between two carbon atoms, with the general chemical formula CnH2n-2.

These are generally hydrophobic but tend to be more reactive.

Alkynes are characteristically more unsaturated than alkenes.


Compounds




Oil Hydrocarbons

The Alkyne members


Compounds




Oil Hydrocarbons

Ethyne (Acetylene)

Ethyne is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne.


Compounds




Oil Hydrocarbons

Preparation of Ethyne


Compounds




Oil Hydrocarbons

Properties of Ethyne

This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution. Pure acetylene is odorless, but commercial grades usually have a marked odour due to impurities.


Compounds




Oil Hydrocarbons

Properties of Ethyne

Element Elements and Compounds Hydrocarbons Mineral Coal and Mineral Oil Compounds A compound is a...

Documents

Transcript of Element Elements and Compounds Hydrocarbons Mineral Coal and Mineral Oil Compounds A compound is a...