Chem

• when you burn a fuel what takes place?

  Combustion
• What is combustion of fuels?

  any chemical potential energy is transferred into heat energy
• List the 4 main fuels

  Methanol, ethanol, propanol, butanol
• What burner are liquid fuels burned in?

  Spirit burner
• We can compare energy content of fuels by measuring

  How much heat energy a certain amount of fuel gives to a certain amount of water
• State the specific heat capalcity of water digit

  4.18
• specific heat capacity of water is defined as

  Energy needed to raise temp of 1kg of water by 1 degree
• Factors affecting diffusion

  concentration gradient, temp, size of molecule, distance, surface area
• how does conc gradient affect diffusion

  the greater the concentration gradient ,the faster the rate
• how does distance affect diffusion

  the further the molecules have to travel the longer it takes so diffusion is quicker over short distances
• semi-permeable membrane affects diffusion..

  increases rate as it only allows small molecules to pass through
• The colour of the fuel darkens as the number of what increases

  Carbon atoms for eCamille petrol is colourless and fuel oil is dark orange
• what happens to the viscosity as the number of carbon atoms increases

  Increases
• does the fuel ignite more easily if there are more carbon atoms

  no it decreases
• Incomplete combustion occurs when there is a ..

  Lack of oxygen in the air
• What is formed by incomplete combustion ?

  Carbon monoxide gas and carbon dioxide known as particulates
• to prevent incomplete combustion cars have

  catalytic converters which converts carbon monoxide in the exhaust gases into carbon dioxide before they are released into the atmosphere
• Coal, crude oil and natural gas are called fossil fuels as they were formed from ?


  the remains of plants or animals which died millions of years ago
• What do fossil fuels all contain

  Sulfur as an impurity which reacts with air to form the gas sulfur dioxide
• Sulphur is an acidic gas because when it reacts with air (water vapour and 02 ) it produces?


  Sulfuric acid which can cause acid rain
• Acid rain causes


  1. Atmospheric pollution

  2. Lakes and rivers to become acidic, killing fish

  3. Soil pH to become too low, killing plants

  4. Trees and plants to lose their leaves (defoliation) reducing their ability to photosynthesise

  5. Limestone buildings and statues to corrode

  6. Iron and steel structures, such as bridges and cars, to rust more quickly
• What is a fuel cell?

  A device that converts chemical energy into electrical energy (hydrogen and Oxygen forms water)
• How is heat energy lost in calorimetry ?

  heat absorbed by calorimeter and lost to surroundings .If incomplete combustion occurs,not all energy available in fuel is transferred to water
• how to improve the calorimetry practical

  Use a bomb calorimeter which is designed to reduce heat loss as it is insulated .The fuel is also burnt in an atmosphere with complete oxygen to ensure complete combustion
• Alkanes


  Saturated hydrocarbons
• Smaller alkanes

  Have lower boiling points (more volatile) than larger alkanes
• The size of the molecules in an alkane will affect its boiling point
• What products are always formed in complete combustion

  Co2 and h20
• Ease of ignition increases as ?

  The number of carbon chains decrease
• what type of heater would maintain constant co2 levels

  Paraffin
• Rate if reaction =

  Amount of product formed /time
• Dynamic equilibrium

  When two processes take place at the same rate so there is no further change in concentration of the substances involved
• what equipment measures volume of solution

  Burettes
• The end point of a reaction is often signalled by a

  Colour change
• In continuous monitoring we

  Take measurements at specific intervals
• Complete combustion

  • Gives a blue flame
  • Produces only carbon dioxide and water
• Removing sulfur dioxide


  React with calcium oxide or calcium carbonate
• Balanced equation for removing sulfur dioxide

  CaO + SO2 → CaSO3
• Catalytic converters

  • Can remove unburned hydrocarbons and nitrous oxides from fuel
• products made by petrochemical industry

  Fuel

  lubricants

  ploymers

  detergents