properties

• what is the general formula for alcohol?

  CnH2n+1OH
• what are alcohols?


  Organic compounds containing a hydroxyl (-OH) functional group.
• are alcohols polar?


  Yes.
• why are alcohols polar?

  the O-H bond is polar, has a permanent dipole due to the difference in electronegativity between O and H.
• why can alcohols dissolve in water?

  the OH group forms hydrogen bonds with water molecules
• how does hydrogen bonding occur?

  labels:

  A) hydrogen

  B) -

  C) +

  
• what is the trend of alcohol solubility in water?

  longer chain alcohols are less soluble in water, because the hydrocarbon chain is not polar and it is more difficult to form hydrogen bonds with water molecules.
• do alcohols have a high volatility?

  no
• why do alcohols have low volatility?

  induced dipole-dipole attractions, hydrogen bonds form between alcohol molecules, meaning more energy needed to separate them than for alkanes.
• why are alcohols less volatile than alkanes?

  the permanent dipole means that there are extra intermolecular forces between alcohols, which don't exist between alkanes of a similar size.
• what can alcohols be classified as?

  Primary, secondary, or tertiary.
• what is a primary alcohol?

  an alcohol in which the hydroxyl (-OH) group is attached to a carbon that is attached to no more than one other carbon e.g. methanol
• primary alcohol?

  labels:

  A) R

  B) OH

  
• what is a secondary alcohol?

  A secondary alcohol is an alcohol in which the carbon atom bonded to the hydroxyl group is attached to two other carbon atoms.
• secondary alcohol?

  labels:

  A) R

  B) R

  
• what is a tertiary alcohol?

  A tertiary alcohol is an alcohol in which the carbon atom bonded to the hydroxyl group is attached to three other carbon atoms.
• tertiary alcohol?

  labels:

  A) R

  B) R

  C) R

  
• what's combustion of alcohols?

  alcohols react with oxygen completely to produce carbon dioxide and water.
• alcohols can be oxidised by what?

  acidified potassium dichromate, K2Cr2O7. Represented as $Cr2O7^2-$
• what agent is potassium dichromate?

  Oxidising agent, represented by [O] in reaction equations
• what do primary alcohols form when oxidised?

  aldehydes and then carboxylic acids
• Under what condition does aldehyde and water form?

  distillation
• under what condition does a carboxylic acid form?

  under reflux with excess Cr2O7^2-
• what do secondary alcohols form when oxidised?


  Ketones
• can tertiary alcohols be oxidised?

  no
• what colour does the oxidising agent change from and to, during the oxidation of alcohols and aldehydes?

  Orange to green
• what reaction occurs when an alcohol forms an alkene?

  elimination reaction, removes the OH group and H atom
• what does elimination reaction require?

  Acid catalyst, concentrated H2SO4 or concentrated H3PO4. With heating under reflux.
• why would two different alkene products form?

  alcohol is unsymmetrical.
• how do alcohols form haloalkane?

  substitution with halide ions in the presence of acid (NaBr/H2SO4)
• mechanism for haloalkane?

  labels:

  A) curly arrow to X

  B) H2O