Brainlag PlusThe alcohols and their reactions, making ethanol by fermentation, carboxylic acids as weak acids, and how an alcohol and an acid make an ester.
Alcohols
Alcohols contain the OH functional group.
The name ends in -ol.
alcohols: CnH2n+1OH
Methanol CH3OH, ethanol C2H5OH, propanol C3H7OH, butanol C4H9OH.
- With sodium: fizzes, giving off hydrogen.
- Burn in air: carbon dioxide and water, so they are used as fuels.
- Small alcohols dissolve in water to give a neutral solution.
- Oxidised (for example by acidified potassium dichromate, or by microbes in air): carboxylic acid with the same number of carbons.
Ethanol is made by fermentation: sugar solution and yeast at about 30 °C, with air kept out. Enzymes in the yeast are the catalyst; above about 40 °C they are denatured.
Balancing an alcohol's combustion, remember the oxygen atom already in the fuel: C2H5OH + 3 O2 → 2 CO2 + 3 H2O.
The rest of this lesson and its 13 practice questions are in Plus.
Screen 1 of 4, free to read.
- 13 exam-style questions, marked as you go, each with a worked solution
- The Molar Mass Calculator beside every question
- Anything you get wrong is saved to your flashcards