Fuels

• When Hydrocarbons are combusted, they release energy in the form of heat as they are oxidized and produce carbon dioxide and water.
• what is crude oil?

  Crude oil is a finite resource containing a mixture of hydrocarbons that can be used as fuels to power many different type of appliances.
• Crude oil can be separated into simpler, more useful substances by fractional distillation.
• The longer the hydrocarbon, the higher the boiling point.
• What are the main types of fractions in crude oil and what are their uses?

  Gas: used for heat and cooking

  Petrol: used as fuel in cars

  Kerosene: used as fuel for planes

  Diesel oil: Used as fuel for heavy machinery

  Fuel oil: Used as fuel for ships and power stations

  Bitumen: used to surface roads
• hydrocarbons in different fractions differ from each other in:

  The number of carbon and hydrogen atoms their molecules contain. boiling points

  ease of ignition

  viscosity (thickness and stickiness).
• A homologous series is a series of compounds which:

  They have the same general formula.

  differ by CH2 in molecular formulae from neighboring compounds.

  show a gradual variation in physical properties, as exemplified by their boiling points.

  have similar chemical properties.
• The size of a Hydrocarbon determines its properties. This is because the intermolecular forces are easier to break when they are smaller. This means that shorter hydrocarbons are easier to ignite.
• If there is a shortage in oxygen, you will get incomplete combustion.
• What are the products of incomplete combustion?

  The products of incomplete combustion are carbon monoxide (CO) and soot (carbon particles).
• Carbon monoxide can restrict the amount of oxygen that can be carried in the blood.
• Soot produced by incomplete combustion can pollute the air and cause respiratory problems.
• Impurities in Hydrocarbon fuels produce pollutants like sulfur dioxide that can cause acid rain.
• Nitrogen and oxygen in the air react with each other to form nitrogen oxides that are caused by the energy of combustion. They are harmful pollutants.
• What are the advantages of using Hydrogen-powered cars?

  Clean, efficient and renewable.
• What are the disadvantages of using hydrogen-powered cars?

  You need a special and expensive engine. Hydrogen is also hard to store.
• methane is a non-renewable fossil fuel found in natural gas.
• What is cracking?

  Cracking is the splitting of long saturated molecules (alkanes) into shorter ones, and shorter unsaturated ones (alkenes) - which are mostly useful.
• Why does the process of cracking require lots of energy?

  It requires a lot of energy so that the bonds are able to break down.
• what catalyst is used in cracking?

  aluminum oxide.
• What temperature is used in cracking?

  400 to 700 C.
• Cracking helps the supply and demand of certain types of hydrocarbons as you can split the less needed ones for the hydrocarbons that are in high demand.