Combustion of Alcohols

• What is the functional group in alcohols?

  -OH
• What are the molecular formulae of methanol, ethanol, propanol and butanol?

  Methanol: CH4O Ethanol: C2H6O Propanol: C3H8O Butanol: C4H10O
• Describe and experiment to investigate the combustion of alcohols

  Heat a copper can containing 100 cm^3 water using a spirit burner, record the temperature of the water and the mass of the spirit burner before and after the experiment, repeat with different alcohols.
• Different alcohols in spirit burners are burnt to heat water in a copper can, what are possible errors in this experiment?

  Heat lost to surroundings, not all flames are the same height from different spirit burners, incomplete combustion, evaporation of alcohols while weighing.
• What safety precautions should be taken when investigating the combustion of alcohols?

  Light the wick of the spirit burner with a splint, don’t move a lit burner, ensure the room is well ventilated, tie back long hair, don’t leave flame unattended.
• When combusting alcohols to heat water, what is the effect on temperature change if the number of carbons in each alcohol molecule increases?

  More carbons in a molecule means a greater increase in temperature.
• How could you measure the temperature of the water more precisely that using a thermometer?

  Use a digital temperature probe to record temperatures to 2 decimal places.
• Different alcohols are being combusted to heat a copper can of water, state 3 factors which must be controlled to allow a fair comparison

  Mass or volume of water, height of copper can above wick, height of flame, shape a copper container, number of moles of alcohol.