Alcohols

• What is the general formula for alcohols?

  CnH2n+1OH
• What is a primary, secondary and tertiary alcohol?

  It’s attached to a carbon with 1, 2 or 3 alkyl groups
• What does the O-H bond being polar mean?

  Electrons are pulled towards the electronegative oxygen in the covalent bond
• How do alcohols interact with water?

  They make hydrogen bonds, the delta positive hydrogen is attracted to lone pairs on neighbouring molecules
• What is the solubility of alcohols?

  Short chain alcohols can dissolve in water
• Why are longer chain alcohols insoluble?

  The longer the carbon chain the more insoluble it is since it’s not polar and reduces the interaction water can make with the alcohol
• Why do alcohols have higher boiling points than molecules of a similar relative mass but with no hydrogen bonding like alkanes?

  Alcohols can hydrogen bond to eachother, its the strongest intermolecular force, alkanes have weaker London forces
• How is a haloalkane made?

  Substitution reaction of an alcohol and a halide ion source (NaBr) with an acid catalyst (H2SO4)
• How is an alkene made?

  Dehydrating an alcohol (removing the OH) using an acid catalyst of sulfuric acid or phosphoric acid
• Why would you make an alkene from an alcohol?

  To make polymers for plastic
• what types of Alkenes can the dehydration of non primary alcohols lead to?

  a double bond can form on either side of the carbon, check for E/Z isomerisation
• What happens in the combustion of alcohols?

  Burn readily with a blue flame, oxidises, can be oxidised with an oxidising agent like acidified potassium dichromate which gets reduced
• What is the colour change in potassium dichromate in combustion of alcohols?

  Orange to green
• What can primary alcohols be oxidised into?

  Aldehydes or carboxylic acids
• What can secondary alcohols be oxidised into?

  Ketones
• How do tertiary alcohols oxidise?

  they cant be oxidised with K2Cr2O7, only by being burned
• How do you extract just the aldehyde when oxidising a primary alcohol?

  Distillation since the aldehyde has a lower boiling point than the alcohol
• How do you make a carboxylic acid when oxidising a primary alcohol?

  Heat under reflux, potassium dichromate, acid,
• How do you show the oxidising agent as a symbol?

  [O]
• Why is reflux used?

  It allows strong heating without losing volatile reactants and products, aldehydes evaporate, condense, then fall back into the flask
• What conditions do you need to oxidise a secondary alcohol into a ketone?

  Reflux
• What is the formula for potassium dichromate?

  K2Cr2O7
• Primary alcohol + H2SO4 + heat =?

  Alkene + water