click below
click below
Normal Size Small Size show me how
Fuels
GCSE chemistry and combined chemistry
Question | Answer |
---|---|
What is crude oil? | A mixture of hydrocarbons |
What is crude oil formed from? | The remains of ancient biomass (mostly plankton) that was buried in mud |
What is a finite resource? Why is crude oil a finite resource? | One that will run out. Because it takes longer to form than the rate at which we are using it up |
What is a hydrocarbon? | A compound made of atoms of carbon and hydrogen only |
What is an alkane? | A hydrocarbon with only single bonds |
Name the first four alkanes | Methane, ethane, propane, butane |
What is the general formula for alkanes? | CnH2n+2 (the n and 2n are small) |
How does boiling point change with the length of an alkane? | The longer the alkane, the higher its boiling point |
How does viscosity change with the length of an alkane? | The longer the alkane, the more viscous (the thicker) it is |
How does flammability change with the length of an alkane? | The longer the alkane, the less flammable it is |
What is fractional distillation? | A process used to separate mixtures of substances with different boiling points |
What are the steps involved in fractional distillation? | Crude oil is vaporised, different molecules rise up the fractionating column and cool down. Condense at different points on the column. |
Why is fractional distillation important? | Because the different fractions have different uses |
What is a fuel? | A substance which when reacted with oxygen releases energy |
Name five fuels we obtain from crude oil | Petrol, diesel oil, kerosene, fuel oil and liquefied petroleum gases |
What other uses are there for products of fractional distillation? | Solvents, lubricants, polymers and detergents |
What is combustion? | The reaction of a fuel with oxygen |
What are the products of complete combustion? | Carbon dioxide and water |
When does incomplete combustion occur? | When there is not enough oxygen present |
What is formed in incomplete combustion | Carbon monoxide |
Why is carbon monoxide dangerous | It is toxic, taken up by red blood cells in preference to oxygen. |
What is cracking? | The process of breaking down a long hydrocarbon into smaller hydrocarbons |
What are the products of cracking? | Short alkanes and alkenes |
Why is cracking important? | Because smaller hydrocarbons are more useful than longer ones |
What are alkenes | A hydrocarbon with a double bond |
What are alkenes used for? | As a starting material to make more useful chemicals |
What is the general formula for alkenes? | CnH2n |
What are the first four alkenes? | Ethene, propene, butene, pentene |
What do members of a homologous series have in common? | Same general formula, differ by CH2 for neighbouring compounds in the series, boiling points increase with chain length, have similar chemical properties and reactions. |
How is sulphur dioxide produced? | Sulphur impurities in fuels form it when the fuel is burnt |
What happens when the sulphur dioxide dissolves in rain water? | Acid rain is formed |
How are oxides of nitrogen formed? | When the nitrogen and oxygen in the air react together at the high temperatures created in combustion engines |
State three advantages of hydrogen fuel cells over petrol | Do not need to be recharged, no pollutants are produced only H2O, water is a renewable resource |
State three disadvantages of hydrogen fuel cells over petrol | Hydrogen is highly flammable, hydrogen is sometimes produced through non-renewable means, hydrogen is difficult to store and transport |
What does finite mean? | It wil run out. |
How does ease of ignition change with the length of an alkane? | The longer the alkane, the harder it is to ignite. |
How are members of a homologous series different from each other? | Their chain length differs by a number of CH2 |
Where do petrol, kerosene and diesel oil come from? | They are obtained by fractional distillation of crude oil |
Where does methane come from? | It is found in natural gas? |
Are petrol, kerosene, diesel and methane renewable or non renewable? | non-renewable |