More Lessons for IGCSE Chemistry
A series of free IGCSE Chemistry Activities and Experiments (Cambridge IGCSE Chemistry).
Reactions of Alcohols
Describe the solubility of alcohols in water
Alcohols are soluble in water and form neutral solutions.
As the number of carbon atoms increases, the solubility decreases.
Describe how the alcohols react with
ethanol + sodium → sodium ethoxide + hydrogen
OH + 2Na → 2C2
ONa + H2
In this reaction, we see bubbles of hydrogen gas produced.
• An oxidising agent
When alcohols react with oxidising agents, they produce a carboxylic acid and water.
Ethanol react with oxidising agent to form ethanoic acid and water.
Balance equations for the combustion of alcohols
Alcohols release energy when combusted. Combusting an alcohol in air produces carbon dioxide and water.
OH + 6O2
Ethanol reacting with Sodium
Reaction of ethanol with sodium metal to form sodium ethoxide and hydrogen. Observations are made, including the appearance of sodium ethoxide.
Oxidation of Ethanol to Ethanoic Acid
Ethanol is oxidised to ethanoic acid by adding cold acidified potassium manganate (VII).
Cold potassium manganate is a moderately strong oxidising agent, and it is reduced to manganese(IV) oxide, which then reacts with the sulphuric acid in solution to produce a brown solution.
Subsequent heating causes the manganese(IV) oxide to further act as an oxidising agent, reducing it to a solution of colourless manganese(II) ions.
Similarities and differences in the combustion of methanol, ethanol and isopropanol (propan-2-ol) are demonstrated
When the combustion is complete, all the hydrocarbons will burn with a blue flame. However, combustion tends to be less complete as the number of carbon atoms in the molecules rises. That means that the bigger the hydrocarbon, the more likely it is to get a yellow, smoky flame.
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