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Chemistry (Organic Chemistry)

Fractions, uses of the Fractions and their Trends​, Four Families of Organic Compounds: Alkanes, Alkenes, Alcohols, Carboxylic Acids and how they are produced​.

Refining Petroleum​

Fractions and Trends

Chain Length, Boiling Points and Viscosity increase down the Fractions. Volatility and Flammability decrease down the Fraction.

  • Refinery Gas has the lowest boiling Point and Viscosity but is the most Volatile and is highly flammable
  • Bitumen has the highest boiling Point and Viscosity but is the least Volatile and is not as flammable as refinery gas

From Text Books

Organic Compounds

Functional Groups

A functional group is an atom or group of atom in a molecule that dictate how the compounds will react.

Homologous Series

A homologous Series is a family of similar compounds that have the same functional group, so have similar chemical Properties.

  • All the compounds fit the same general formula.
  • The compounds show a trend in physical properties, as the chain gets longer. Melting and boiling points rise. Viscosity increases – they flow less easily. Flammability decreases – they burn less easily 

From Text Books

Reactions between the four Organic Compound Families 

From Text Books

Alkanes

Alkanes contain only carbon and hydrogen, so they are hydrocarbons. The bonds between their carbon atoms are all single bonds. Alkanes are saturated as they only have a single carbon bond. (General Formula: CnH2n+2 )

Here are the First 6 Alkanes:
  1. Methane (CH4)
  2. Ethane (C2H6)
  3. Propane (C3H8)
  1. Butane (C4H10)
  2. Pentane (C5H12)
  3. Hexane (C6H14)

From Text Books

Alkenes

Alkanes contain only carbon and hydrogen, so they are also hydrocarbons. All alkenes contain carbon – carbon double bonds. Alkanes are unsaturated as they only have a double carbon bond. (General Formula: CnH2n ) 

Formation of Alkenes:

Alkenes can be formed by cracking Alkanes with steam and temperatures above 800 degrees Celcius. 

Test for Alkenes:

Alkenes can be tested using Bromine Water. The orange colour of the solution turns colourless when alkenes are added due to addition reaction.

Here are the First 6 Alkenes:
  1. Ethene (C2H4)
  2. Propene (C3H6)
  3. Butene (C4H8)
  1. Pentene (C5H10)
  2. Hexene (C6H12)
  3. Heptene (C7H14)

From Text Books

Alcohols​

The alcohols are not hydrocarbons. They are like the alkanes, but with an OH group. The OH group is their functional group. (General Formula: CnH2n+1 OH). Ethanol can be formed by fermentation or by Hydration.

Fermentation:

(Glucose ➜ Ethanol + Carbon dioxide + Energy)(Conditions: 25-35°C, Enzymes in Yeast)

Hydration:

(Ethene + Water ➜ Ethanol) (Conditions: 570°C, 50-60 ATM and Phosphoric Acid as catalyst)

Uses of Alcohols:
  1. It is a good solvent. It dissolves many substances that do not dissolve in water.
  2. Burns Readily in Oxygen and gives out a lot of heat. Hence, they can be used as fuel.
  3. It can be used in sanitizers and wipes, as it can kill bacteria and viruses.
Here are the First 4 Alcohols:
  1. Methanol (CH3OH)
  2. Ethanol (C2H5OH)
  1. Propanol (C4H7OH)
  2. Butanol (C4H9OH)

From Text Books

Carboxylic acids

The carboxylic acids are also not hydrocarbons, as they don’t have any hydrogen and carbon atoms. All carboxylic acids contain the COOH group. COOH is their functional group. (General Formula: CnH2nO2)

Formation of Carboxylic acids:

Carboxylic Acids are formed when Ethanol is left standing in air and bacteria oxidises it. This is called Fermentation.

Here are the First 4 Carboxylic acids:
  1. Methanoic (HCOOH)
  2. Ethanoic (CH3COOH)
  1. Propanoic (C2H5COOH)
  2. Butanoic (C3H7COOH)

Esters

Carboxylic Acids react with Alcohols to give compounds called Esters. The Esters name contains the Alcohol First and the Acid at the last. An Example: Propyl Ethanoate.

  • Carboxylic Acid + Alcohol ⇌ Ester + Water
  • Ethanoic Acid + Propanol ⇌ Propyl Ethanoate + Water

From Text Books

Current Chapter: Organic Chemistry

Acids and Bases

Acids and Alkalis, Colour Changes in Indicators, Reactions of Acids and Bases, Acidic Oxides and Basic Oxides.

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Chemistry (Notes)

Notes for Chemistry Theory and Alternative to Practical. Contents: Periodic Table, Reactions, Extracting Metals, Acids and Bases and Organic Chemistry...

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