CARBON AND ITS COMPOUNDS


Carbon is a chemical element with symbol C and atomic 6. As a member of group of  4 on the periodic table, it is nonmetallic and tetravalent i.e making four electrons available to form covalent chemical bonds.
There three naturally occurring isotopes of carbon;
(i) 13C
(ii)12C
(iii)14C which is radioactive, decaying with half-life of about 5730 years.

ALLOTROPES OF CARBON.
There are several allotropes of carbon, but the common ones are;
(i) Graphite
(ii)Diamond
(iii)Amorphous carbon.
The rest which are not well known include
(i)Carbon nanotubes
(ii)Carbon nanobuds
(iii)Vitrious carbon
(iv)Atomic and diatomic carbon
(v)Carbon nanoform
(vi) Ionsdaleite etc.

DIAMOND


The carbon atoms are arranged in a variation of the face – centered cubic crystal stretcher called diamond lattice.
It has the highest hardness and thermal conductivity of any bulky material due to its strong covalent bonding between its atoms.
These properties determine the major industrial application of diamond in cutting and polishing tools.
It has relatively high optical dispersion (ability to disperse light of different colors) which results in its characteristic luster (the way light interacts with the surface of crystal, rock or mineral)
Above 17000c in vacuum or oxygen-free atmosphere, diamond converts into graphite.
Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen.
Naturally occurring diamonds have a density ranging from 3.15 – 3.53 g/cm³ with pure diamond close to 3.52 g/cm³.
Diamond being very stable at room temperature it does not react with any chemical reagents including various kinds of acid and alkali.
Pure diamond does not conduct electricity; it only conducts when doped with other impurities such as boron and nitrogen.
Diamond can be of color black, translucent white, pink, violet, orange or purple.

USES OF DIAMOND


i) Used as jewelry due to their shiny luster.
ii) Geologically diamond can be used to determine age of universe.
iii) Being the hardest compound its used to cut metals and making drill tips

GRAPHITE


Unlike diamond graphite is an electrical conductor.
It is consequently useful in such applications as electrodes in chemical cells.
It is also the most stable form of carbon under standard conditions. Therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds.
There three principal types of natural graphite each occurring different types of ore deposit;
(i)Crystalline flake graphite – occurs as isolated, flat, plate like particles with hexagonal edges.
(ii)Amorphous graphite – occurs as fine particles and it’s the result of thermal metamorphism of coal.
(iii)Lump graphite – occurs in veins or fractures.
Graphite has a layered, planar structured. In each layer the carbon atoms are arranged in a hexagonal lattice with separation of 0.142 nm and the distance between planes is 0.335nm.
It can conduct electricity due to the vast electron delocalization within the carbon layers. It has lubrication properties due to the pressure of fluids between the layers naturally absorbed from the environment.

USES OF GRAPHITE


i) Used for conducting both electricity and heat.
ii) it’s used as a solid lubricant.
iii)used in manufacture of brake linings

AMORPHOUS CARBON


It does not have any crystalline structure.
As with all other glassy materials, some short range order can be observed.
The properties of amorphous carbon vary depending on the parameter used during deposition.

OXIDES OF CARBON


Carbon forms two well known oxides which are;
(i) Carbon monoxide (CO)
(ii)Carbon dioxide (CO2)
In addition it forms carbon suboxide (C3O2 )

CARBON MONOXIDE


It is produced when graphite is heated or burned in a limited amount of oxygen.
The reaction of steam with red-hot coke also produces carbon monoxide along with hydrogen gas.
The mixture of CO and H2 gas is called the water gas and is used as an industrial fuel.
In the laboratory CO is prepared by heating formic acid (HCOOH) or oxalic acid (H2C2O4) with concentrated sulphuric acid, (H2SO4). The sulphuric acid removes the elements of water (H2O) from the two acids and absorbs the water produced.
Because carbon monoxide burns readily in oxygen to produce carbon dioxide;
2CO + O2 2CO2(g). it is useful as fuel.
It is also used as a metallurgical reducing agent because at high temperature it reduces many metal oxides into the elemental metal eg CUO and Fe2O3 are reduced to CU and Fe respectively.
CO is extremery dangerous poison. It binds to the hemoglobin in blood to form a compound that is so stable that it cannot be broken down by the body processes. The hemoglobin cannot combine with oxygen and this makes transportation of oxygen to body parts difficult leading to suffocation. Because of it is odourless and tasteless; it gives no warning of its presence.

USES OF CARBON MONOXIDE


i)used as reducing agent
ii)in form of water gas its widely used as fuel in industrial operations.

CARBON (IV) OXIDE


It is produced when any form of carbon or almost any carbon compound is burned in excess oxygen.
Also metal carbonates liberate CO2 when heated eg Calcium carbonate decomposes to carbon calcium oxide and carbon dioxide.
The fermentation of glucose (a sugar) during the preparation of ethanol produces large quantities of CO2 gas as by products.
C6H12O6 C2H5OH + CO2
In the laboratory CO2 can be prepared by adding a metal carbonate to an aqueous acid.
It is a colorless and essentially oduorless that is 1.5 as dense as air.
It is not toxic although a large concentration could result in suffocation.

USES OF CARBON DIOXIDE
i) used in extinguishers.
ii) used to make carbonated soft drinks and soda water.
iii)As a solvent – liquid CO2 is considered a good dissolving agent for organic compounds.
iv)In metal industry – CO2 is used in manufacture of casting influence as to enhance their hardness.