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Alcohols. Similar to Hydrocarbons except for one group of chemicals. OH group. Hydroxyl group. Alcohols. The hydroxyl group gives the Alcohols some properties that are different to Hydrocarbons. Other properties of Alcohols are very similar to Hydrocarbons. Alcohols. Naming. Prefix
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Alcohols • Similar to Hydrocarbons except for one group of chemicals. • OH group. • Hydroxyl group
Alcohols • The hydroxyl group gives the Alcohols some properties that are different to Hydrocarbons. • Other properties of Alcohols are very similar to Hydrocarbons.
Alcohols • Naming Prefix Same as hydrocarbons Suffix -anol
H H H C C OH H H Alcohol 2 Carbons – Eth -OH group – anol Name Ethanol
H H C OH H Alcohol 1 Carbon – Meth -OH group – anol Name Methanol
Alcohols • Physical Properties • Boiling and Melting Points • The boiling and melting points of Alcohols are higher than similar hydrocarbons
Alcohol • Methane BP -161oC • Methanol BP 65oC • Ethane BP -89oC • Ethanol BP 78oC
Alcohols • Why do Alcohols have a much higher BP than Hydrocarbons? • The only difference is the –OH group in Alcohols. • The –OH group means that a stronger type of bond can form between molecules in Alcohols –a hydrogen bond
Alcohols • Hydrogen bonds require a lot of energy to break so the Melting and Boiling Points of Alcohols are high.
Alcohols • Hydrocarbons do not dissolve in water. • Oil floats on top of water. • They are insoluble in water • Alcohols dissolve in water. • It is soluble in water • The reason once again is the –OH group.
Alcohols • Water is a Polar compound. • It has +ve end and a –ve end. • Polar compounds can dissolve in water. • Non-polar compounds cannot dissolve in water. • The –OH group makes Alcohols polar compounds. • Hydrocarbons are non-polar.
Alcohols • Alcohols burn the same way as Hydrocarbons. • Complete combustion – CO2 + H2O • Incomplete combustion – C, CO + H2O
Alcohols • Reactions • Combustion- Complete • With plentiful Oxygen Alcohols burn and produce water and carbon dioxide Ethanol + oxygen → water + carbon dioxide C2H5OH + 3O2→ 3H2O + 2CO2