Alcohols

• General Formula?

  CnH2n+1OH
• The bind angle of C-O-H is 104.5 because?

  Lone pair repulsion
• Why do alcohols have a higher boiling point?

  The OH group means that hydrogen bonding occurs between molecules, so alcohols have higher boiling/melting points than alkanes of similar relative molecular mass.
• Does solubility of alcohols increase or decrease as the chain gets longer? Why?

  Short-chain alcohols are more soluble in water as hydrogen bonding is the main attraction between molecules. As the alcohols get larger, the non-polar hydrocarbon chain becomes more dominant and alcohols become insoluble.
• What makes an alcohols primary?

  1 carbon attached to the carbon adjoining the oxygen
• What makes an alcohols secondary?

  2 carbons attached to the carbon adjoining the oxygen
• What makes an alcohol tertiary?

  3 carbons are attached to the carbon adjoining the oxygen
• What are the two methods for producing ethanol?

  Fermentation and Ethene
• What are the conditions for fermentation?

  Yeast (enzyme)

  No O2 (anaerobic)

  30-40 (optimum 35- body temp)
• What are the advantages to using fermentation to produce ethanol?

  Sugar is a renewable source, the process is carbon neutral

  $6H2O\ +$$\ 6CO2\ \rightarrow\ C6H12O6\ +$$6O2$

  $C6H12O6\ \rightarrow2C2H5OH\ +$$2CO2\ \left(fermentation\right)$

  $2C2H5OH\ +$$6O2\ \rightarrow\ 4CO2\ +$$6H2O\ \left(combustion\right)$
• What are disadvantages to using fermentation to produce ethanol?

  Batch process which is slow and costly

  Ethanol is not pure and needs fractional distillation to purify it before use as biofuel

  Takes up land for growing food
• What are the conditions for making ethanol from ethene?

  Higher temperature -300

  High pressure -70atm

  Strong acidic catalyst H3PO4
• What is the equation for making ethanol from ethene?

  Ethene + steam -> ethanol
• What are the advantages of using ethene to form ethanol?

  Continuous flow process- more efficient

  Fast reaction

  Pure product
• What are the disadvantages of using ethene to form ethanol?

  Uses finite resources (non-renewable) based on crude oil

  High energy costs to produce high pressure

  High technology equipment is expensive
• What is the equation for the complete combustion of ethanol?

  $C2H5OH\ +$$3O2\ \rightarrow\ 2CO2\ +$$3H2O$
• Distillation

  Achieves partial oxidation, use a heater instead of bunsen (safer). Water in at the bottom of the condenser because liquid travels downwards allows it to be fully cooled.
• Reflux

  Prevents organic vapours from escaping and to ensure the alcohols is fully oxidised before distilling off the product.

  Anti bumping granules control the size of the bubble
• What is the oxididsing agent used for alcohols?

  Acidified potassium dichromate
• What is the colour change of acidified potassium dichromate?

  orange to dark green

  Cr is reduced from 6+ to 2+