ORGANIC CHEMISTRY

MAINLY THE STUDY OF CARBON COMPOUNDS IS CALLED ORGANIC CHEMISTRY,BECAUSE ALL LIVING ORGANISM DEPEND ON CARBON COMPOUNDS FOR THEIR EXISTANCE.TODAY, CHEMISTS CAN ALSO CREAT SYNTHETIC CARBON COMPOUNDS.NATURAL & SYNTHETHIC COMPOUNDS OCCUR IN A WIDE RANGE OF MATERIALS, SUCH AS FOOD,FUEL,PAINT,TEXTILES AND PLASTICS.

THERE ARE MAINLY TWO KINDS OF ORGANIC CHEMICALS.THEY ARE DESCRIBED BELLOW-

1. ALIPHATICS-

ORGANIC CHEMICALS CONTAINING A CHAIN OF CARBON ATOMS LINKED BY SINGLE,DOUBLE OR TRIPLE BONDS ARE CALLED ALIPHATICS.THE ELIPHATIC ETHANE OCCURS IN NATURAL GAS, AND ETHENE IS USED TO MAKE PLASTICS.

2. AROMATICS-

THE STRONG-SMELLING ORGANIC COMPOUNDS CALLED AROMATICS CONTAIN A RING OF SIX CARBON ATOMS.BENZEN, THE SIMPLEST AROMATIC,IS A COLOURLESS LIQUID OBTAINED FROM COAL,NATURAL GAS AND PETROLEUM.AROMATICS ARE USED TO MAKE VIVID DYES CALLED ANILINES.

FATS & OILS-

LIQUID VEGETABLE OIL IS AN UNSATURATED FAT- A TYPE OF FAT IN WHICH SOME OF THE CARBON ATOMS ARE LINKED BY DOUBLE BONDS..WHEN THE OIL REACTS WITH HYDROGEN,THE DOUBLE BONDS BREAK AND THE CARBON ATOMS LINK UP WITH EXTRA HYDROGEN ATOMS,FORMING A SOLID FAT SUCH AS MARGARINE.SOLID FATS CONTAIN ONLY SINGLE BONDS BETWEEN THEIR CARBON ATOMS.THESE FATS ARE SAID TO BE SATURATED BECAUSE THEY CANNOT BOND WITH MORE HYDROGEN ATOMS.

POLYMERS-

POLYMERS ARE GIANT MOLECULES THAT CONSISTS OF WINDING CHAINS OF THOUSANDS OF SMALL ORGANIC MOLECULES CALLED MONOMERS.FATS,STARCHES,PLASTICS AND ARTIFICIAL FIBERS ARE MADE OF MANY ETHENE MONOMERS JOINED TOGETHER.

GEOCHEMISTRY

THE EARTH’S COMPOSITION AND THE CHEMICAL STRUCTURE OF ROCKS ARE STUDIED IN GEOCHEMISTRY.THE FINDINGS OF GEOCHEMISTS GIVE US A GREATER KNOWLEDGE OF THE EARTH’S HISTORY AND HELP US TO FIND ORES, MINERALS, AND OTHER RESOURCES.

BIOCHEMISTRY

THE STUDY OF THE CHEMISTRY OF LIVING ORGANISMS AND THE CHEMICAL PROCESSES, SUCH AS RESPIRATION,THAT TAKE PLACE WITHIN THEM IS CALLED BIOCHEMISTRY.THE DISCOVERIES OF BIOCHEMISTS ARE USED IN INDUSTRY, MEDICINE, AND AGRICULTURE

ELECTROCHEMISTRY

THE STUDY OF THE RELATIONSHIP BETWEEN ELECTRICITY AND CHEMICAL SUBSTANCES IS CALLED ELECTROCHEMISTRY.MANY COMPOUNDS CONSIST OF ELECTRICALLY CHARGED PARTICLES CALLED IONS WHICH FORM WHEN ATOMS LOSE OR GAIN ELECTRONS.A BATTERY USES A CHEMICAL REACTION TO GENERATE AN ELECTRIC CURRENT.

CHEMICAL INDUSTRY

THE CHEMICAL INDUSTRY IS ONE OF THE LARGEST AND THE MOST IMPORTANT INDUSTRIES OF THE WORLD.IT INVOLVES TAKING NEW MATERIALS-SUCH AS AIR,OIL,WATER,COAL,METAL ORES,LIMESTONE AND PLANTS- AND USING CHEMICAL REACTIONS TO CHANGE THEM INTO USEFUL PRODUCTS.THESE INCLUDE FOOD,CLOTHING,MEDICINE,PESTICIDES AND FERTILIZERS,PAINTS AND DYES,SOAPS AND DETERGENTS,PLASTICS AND GLASSWARE

CATALYSTS

COMPOUNDS CALLED CATALYSTS SPEED UP A CHEMICAL REACTION BY HELPING SUBSTANCES REACT TOGETHER.THE CATALYSTS ARE LEFT UNCHANGED BY THE REACTION.MANY CARS ARE FITTED WITH A CATALYTIC CONVERTER TO REMOVE POLLUTING GASES FROM ENGINE FUMES.THE CONVERTER FORCES THE GASES INTO CLOSE CONTACT WITH CATALYSTS.THE CATALYSTS MAKE THE GASES REACT RAPIDLY WITH EACH OTHER,PRODUCING LESS HARMFUL GASES THAT ESCAPE OUT OF THE EXHAUST PIPE.

RATES OF REACTIONS

REACTIONS CAN BE SPEEDED UP BY MAKING THE REACTING PARTICLES COME INTO CONTACT WITHH EACH OTHER MORE OFTEN.ONE WAY OF DOING THIS IS BY INCREASING A REACTANT'S SURFACE AREA.SULPHURIC ACID REACTS MORE RAPIDLY WITH CHALK PIECES,BECAUSE THE POWDER HAS A GRATER SURFACE AREA.

CHEMICAL REACTIONS

DURING CHEMICAL REACTION,SUBSTANCES CALLED REACTANTS BREAK APART & NEW SUBSTANCES CALLED PRODUCTS FORM.ENERGY IS TAKEN INTO BREAK THE BONDS BETWEEN THE REACTANTS ATOMS.AS THE ATOMS LINK UP AGAIN IN DIFFERENT COMBINATIONS TO MAKE THE PRODUCTS, NEW BONDS FORM THE ENERGY IS GIVEN OUT.

THERE ARE MANY KINDS OF REACTIONS.THEY ARE DESCRIBED BELLOW-

1. EXOTHERMIC REACTIONS-

IN AN EXOTHERMIC REACTION,SUCH AS BURNING,MORE ENERGY IS GIVEN OUT THAN IS TAKEN IN FROM THE SURROUNDINGS.

2. ENDOTHERMIC REACTIONS-

MOST OF THE REACTIONS THAT OCCUR IN COOKING ARE ENDOTHERMIC,WHICH MEANS THAT MORE ENERGY IS TAKEN IN THAN IS GIVEN OUT.

3. OXIDATION & REDUCTION-

WHEN IRON RUSTS, A REACTION OCCUR BETWEEN THE IRON & OXYGEN IN THE AIR.THE IRON GAINS OXYGEN, AND AN ORANGE-BROWN COMPOUND CALLED IRON OXIDE FORMS.A REACTION IN WHICH A SUBSTANCE GAINS OXYGEN IS CALLED OXIDATION.WHEN OXIDATION OCCURS, THERE IS A SIMULTANIOUS REACTION CALLED REDUCTION, IN WHICH A SUBSTANCE LOSES OXYGEN.WHEN IRON OXIDIZES, THE AIR IS REDUCED AS IT LOSES OXYGEN TO IRON.

4. REVERSIBLE REACTIONS-

MANY CHEMICAL REACTIONS PERMANENTLY CHANGE THE REACTANTS, BUT REVERSIBLE REACTIONS CAN GO BOTH FORWARDS AND BACKWARDS.FOR EXAMPLE WHEN NITROGEN DIOXIDE IS HEATED, IT BREAKS DOWN INTO NITROGEN MONOXIDE AND OXYGEN.COOLING THIS MIXTURE MAKES THE TWO GASES REACT TO FORM NITROGEN DIOXIDE AGAIN.

CHEMICAL EQUATIONS

SCIENTISTS WRITE CHEMICAL EQUATIONS TO DESCRIBE WHAT HAPPENS DURING A CHEMICAL REACTION.IT TELLS EXACTLY WHATS HAPPENING IN A REACTION.FOR EXAMPLE- WHEN TWO ATOM OF HYDROGEN AND ONE ATOM OF OXYGEN ARE BONDED TOGETHER THROUGH A REACTION THEN WATER IS CREATED.AS A MATTER AFFECT THIS BOND CAN NOT CREATED WITHOUT A CHEMICAL REACTION.HOWEVER,THIS CHEMICAL REACTION CAN BE DESCRIBED BY THE EQUATION BELLOW-

2H2 + O2 = 2H2O