Chemistry Revision: Organic Chemistry

HideShow resource information

Introduction

Organic Chemistry consists of molecules containing primarily carbon and hydrogen

A molecule containing only carbon and hydrogen is known as a hydrocarbon

Other common elements used in organic compounds are nitrogen, oxygen, and the halogens (Group 7)

WORTH MENTIONING: THE COMPOSITION OF AIR

78% Nitrogen, 20% Oxygen, 1% Carbon Dioxide, 1% other gases

1 of 9

Hydrocarbons

Formula for calculating Hydrogen atoms: CnH(2n+2)

Example: CH4,C2H6, etc...

Isomers

Isomers have the same molecular formula but different arrangements in space (different structural formula)

Example: 

(http://upload.wikimedia.org/wikipedia/commons/1/1b/Isomeren.png)

2 of 9

Homologous Series

A homologous series is a series of organic compounds with a similar general formula

They possess similar chemical properties due to the presence of the same functional group

HOWEVER they have different chemical properties as a result of increase in mass and molecular size

EXAMPLE- Alkenes only have 1 double bond

Alkene formula=CnH2n

Alkane formula= CnH(2n+2) 

ALKENES ARE UNSATURATED (CAN MAKE MORE BONDS)

ALKANES ARE SATURATED (CAN NO LONGER MAKE BONDS)

3 of 9

Crude Oil

Formation:

Millions of years ago dead marine animals and plants formed a layer of sediment on the sea bed. This layer was buried by a deposit of mud and rock fragments. Heat and pressure from the overlaying layers of rock decayed the organic matter in anaerobic conditions and formed a pocket of gas and oil, The gas and oil passed through the porous rock collected beneath layers of non-porous rock.

Conditions:

  • Animal Remains
  • HIGH Temperature
  • HIGH Pressure
  • Anaerobic conditions
  • Millions of years

Extraction:
Drill through the inpermeable layer to release the oil which is then extracted by being pumped up to the surface. 

4 of 9

Fractional Distillation of Crude Oil (on an indust

The oil is heated to about 400degrees until it vaporises and passes into a fractionating column.

The fractionating column has a temperature gradient, cooler towards the top.

As the vapour rises up the column, groups of alkanes reach a temperature cool enough to allow them to condense. The smaller alkanes condense towards the top of the column.

Each group of alkanes will condense within the column at a specific height which is determined by its boiling point.

The liquid alkanes are then topped off from the column in seperate fractions.

5 of 9

Polymers

Polymers are long chain molecules, formed by reacting lots of short chain molecules, or monomers (e.g. alkenes), together

TEST FOR SATURATION: REACT BROMINE WATER WITH A HYDROCARBON:  IF THE BROMINE TURNS COLOURLESS, THEN THE REACTANT WAS UNSATURATED.

Polymerisation- Alkenes undergo this to form various plastics. It is the name of when monomers join together to form polymers.

The monomers MUST have a double bond, only alkenes will be used at GCSE.

Uses- Poly(e)thene=Shopping bags/buckets,Polypropene=Milk crates/Rope,Polystyrene=Packing/Insulation

INTERMOLECULAR FORCES- The strength of forces between polymer chains depends on:

  • The monomer used
  • Conditions chosen for polymerisation

THERMOSETTING POLYMERS AND THERMOSOFTENING POLYMERS

6 of 9

Manufacturing of Ethanol

2 methods: FERMENTATION OF SUGARS and HYDRATION OF ETHENE

FERMENTATION OF SUGARS: 
Sugars dissolved in water>yeast added to the mixture>Mixture maintained between 30 and 40 degrees
Yeast produces enzymes, the biological catalysts. Sugars produce ethanol and carbon dioxide
Glucose=Ethanol + Carbon Dioxide (ANAEROBIC)

Advantages: Renewable, suitable for drink manufacture
Disadvantages: Batch process, takes longer, only 15% ethanol

HYDRATION OF ETHENE
Crude oil fractionally distilled>Fractions of alkanes cracked>Ethene + Small alkane hydrated>Ethanol

Advantages:Fast,Continuous,Suitable as fuel, almost pure ethanol
Disadvantages: Non-renewable, requires high temperature 

7 of 9

Carboxylic Acids- Weak Acids (Less H signs)

GENERAL FORMULA=RCOOH, WHERE R=THE FUNCTIONAL GROUP (WHAT MAKES THE CHAIN REACT IN A CERTAIN WAY)

METHANOIC ACID=HCOOH

ETHANOIC ACID=CH3COOH MAIN COMPONENT OF VINEGAR, WHEN REACTED WITH AN ACID FORMS A SALT AND WATER

REACTIONS OF ETHANOIC ACID WITH ALKALIS/CARBONATES + METALS FORMS ETHANOATE SALTS

IF CO2 IS RELEASED WITH A METAL CARBONATE OR METAL HYDROGEN METAL CARBONATE THEN THIS SHOWS THE PRESENCE OF CARBOXYLIC ACIDS.

FORMED BY WARMING ALCOHOLS WITH AN OXIDISING AGENT

8 of 9

Esters

FORMED BY THE REACTION OF CARBOXYLIC ACIDS WITH ALCOHOLS 

(http://www.materialsworldmodules.org/resources/polimarization/esterlinkeqn.gif)

THE PREFIX OF THE NAME COMES FROM THE ALCOHOL GROUP

THE SUFFIX COMES FROM THE CARBOXYLIC ACID

EXAMPLE:

ETHANOIC ACID + METHANOL= METHYL ETHANOATE

CH3COOH

9 of 9

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Organic and Green Chemistry resources »