chemistry module 4 alcohols

Alcohols

Compounds containing at least one hydroxy (-OH) group.

General Formula

CₙH₂ₙ₊₁OH for alcohols.

Hydrogen Bonding

Attraction between hydrogen and electronegative atoms.

Intermolecular Forces

Forces between molecules affecting physical properties.

Boiling Point

Temperature where liquid turns to vapor.

Propane Boiling Point

-42°C, lower than propanol.

Propanol Boiling Point

97°C, higher due to hydrogen bonding.

Temporary Induced Dipole-Dipole Forces

Weak forces from temporary dipoles in molecules.

Solubility of Alcohols

Small alcohols are completely soluble in water.

Hydrocarbon Chain Effect

Longer chains reduce solubility in water.

Primary Alcohols

-OH group attached to a carbon with one alkyl group.

Secondary Alcohols

-OH group attached to a carbon with two alkyl groups.

Tertiary Alcohols

-OH group attached to a carbon with three alkyl groups.

Combustion of Alcohols

Reaction with oxygen producing CO₂ and water.

Ethanol as Fuel

Produced sustainably from fermentation of sugars.

Energy Density

Energy content in kJ per kg of fuel.

Oxidation of Primary Alcohols

Forms aldehydes, which can further oxidize to carboxylic acids.

Oxidation of Secondary Alcohols

Forms ketones, cannot oxidize further.

Tertiary Alcohols Oxidation

Do not undergo oxidation reactions.

Oxidizing Agents

Substances like K₂Cr₂O₇ or KMnO₄ that oxidize alcohols.

Color Change of K₂Cr₂O₇

Orange to green when oxidizing alcohols.

Color Change of KMnO₄

Purple to colorless when oxidizing alcohols.

Dehydration Reaction

Alcohol loses water to form alkenes.

Catalysts for Dehydration

Al₂O₃ or concentrated sulfuric acid used.

Substitution Reaction

-OH group replaced by a halogen.

Haloalkanes

Compounds formed from alcohols via substitution.

Bromoethane Formation

Ethanol reacts with PBr₃ to form bromoethane.

Hydrolysis Reaction

Water reacts to remove excess PBr₃.