alkanes

• what is homologous series

  a series of compounds which have

  the same general formula

  similar chemical properties

  slight variation in physical properties
• products from crude oil mostly belong to what homologous series

  alkane homologous series
• what are the products when a hydrocarbon fuel undergoes complete combustion

  water and carbon dioxide
• what type of reaction is complete combustion

  exothermic ( gives out energy )
• when does complete combustion occur

  it occurs when there is a sufficient amount of oxygen for a full reaction to happen
• when does incomplete combustion occur

  incomplete combustion occurs when theres an insufficient supply of oxygen
• what are the products of incomplete combustion

  carbon particulates (soot)

  carbon monoxide

  water
• what are the dangers with carbon monoxide

  it is a toxic gas

  it is colourless and odourless and if it is breathed in it can cause death as it will bind to haemoglobin instead of oxygen in the blood starving the body of oxygen
• what are the problems with incomplete combustion

  produces carbon monoxide which is a toxic gas and can be fatal if breathed in

  produces soot which can cause global dimming and respiratory problems
• how do properties of hydrocarbons differ as you go up the fractionating column

  as you go up the chains get shorter , the longer hydrocarbons have a higher viscosity , the longer hydrocarbons have less volaitily and flammability as they are liquids at room temperature
• why is sulfur dioxide sometimes produced when burning hydrocarbon fuels

  some hydrocarbons contain sulfur impurities , when the fuel is burned , the sulfur reaccts with oxygen to form sulfur dioxide
• how is acid rain produced

  sulfur dioxide evaporates into the air , it reacts with water in the clouds to form sulfuric acid , this is acid rain
• what problems can acid rain cause

  corrodes buildings and statues made of limestone

  kills damages the vegetation

  lowers the ph of large bodies of water killing wildlife
• how are oxides of nitrogen produced 


  the high temperature and pressure of a car engine causes nitrogen and oxygen from the air to react together
• what are the problems associated with the oxides of nitrogen

  pollutants , produce rain with similar effects as so2

  cause respiratory problems
• what are the advantages of using hydrogen as a fuel in cars

  it releases more energy per kilograms compared to other fuels , water is the only product so there are no pollutants

  renewable source as hydrogen can be extracted from water
• disadvantages of using hydrogen in cars as fuel

  it is expensive to produce and a lot of energy is required for the electrolysis of water to acquire the hydrogen

  it is difficult and dangerous to store hydrogen because it is very volatile and it easily ignites
• name the non renewable fossil fuel found in natural gas

  methane
• are petrol kerosene and diesel non renewable fossil fuels obtained from crude oil

  yes
• what is cracking 


  breaking down large hydrocarbons into smaller useful ones

  saturated alkanes are cracked into shorter chain alkanes and unsaturated alkenes
• what does the term saturated mean in hydrocarbons

  only contains carbon carbon single bonds
• what does the term unsaturated mean

  they contain some carbon carbon double bonds
• what type of reaction is cracking

  thermal decomposition
• why is cracking necessary

  the demand for short chain alkenes is much higher than the demand for long chain alkenes