Chemistry

Structures and Properties of Alcohols

  • Alcohols contain the functional group -O-H. If one hydrogen atom from each alkane molecule is replaced with an -O-H group, we get a homologous series of alcohols.
  • First three members of this series and methanol, ethanol and propanol.
  • A structural formula shows which atoms are bonded to each carbon atom and the functional group. The structural formula of ethanol is CH3CH2OH.

Properties:

  • Good solvents
  • Burn easily
  • mix with water to produce a neutral solution- covalent molecule = no ions!
  • oxidised easily- potassium dichromate- carboxylic acid.
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Structures and Properties of Carboxylic Acids

  • Formed by the the oxidation of alcohols with potassium dichromate
  • Carboxylic acids react with metal carbonates producing a salt plus water and carbon dioxide.

Ethanoic acid + sodium carbonate = sodium ethanoate + water + carbon dioxide

  • Carboxylic acids have the functional group -COOH.
  • The first three members of the carboxylic acids are methanoic acid, ethanoic acid and propanoic acid. Their structural formule are HCOOH, CH3COOH and CH3CH2COOH.

properties:

  • Mixed with water = acids
  • react with metals

Carboxylic acid + Alcohol + Ester

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Structures and Properties of Esters

  • Esters are formed when an alcohol with a carboxylic acid react in the prsence of an acid catalyst.

Ethanoic Acid + Ethanol =( sulfuric acid catalyst)= Ethly ethanoate + Water

  • They have a functional group of -COO-. If the H atom in the -COOH group of a carboxylic acid is replaced by a hydrocarbongroup the compound is an ester.
  • Ethyl ethanoate has the structural formula CH3COOCH2CH3.

Esters are used in flavourings and perfumes as they have a very distinctive smell.

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