Chemistry-Natures Flashcards
Revision
What is a fuel?
A fuel is a substance that burns releasing energy.
What does combustion refer to?
Combustion is a chemical word for burning.
What happens when a substance burns?
All the elements present are combined with oxygen to produce the relevant oxides.
What is essential for combustion?
Oxygen is essential for combustion.
What does the fire triangle represent?
The key elements needed for burning.
What happens if one element of the fire triangle is removed?
The fire goes out.
How do firefighters put out fires?
By removing one of the elements of the fire triangle.
What effect does putting water on a fire have?
It removes the heat.
Why is carbon dioxide used to extinguish fires?
It is heavier than oxygen, sinks, and stops oxygen getting in.
What does cutting down trees in a forest fire do?
It removes fuel.
What is a hydrocarbon?
A molecule that contains carbon and hydrogen.
What is produced when a hydrocarbon is burned in a plentiful supply of oxygen?
Carbon dioxide and water (complete combustion).
What is produced during incomplete combustion of a hydrocarbon?
Carbon monoxide, soot (unburnt carbon), carbon dioxide, and water.
What are fossil fuels, and how long did they take to form?
Fossil fuels such as coal, oil, and gas took millions of years to form and are finite.
What gas is produced by burning fossil fuels that contributes to global warming?
Carbon dioxide, which is a greenhouse gas.
What is the environmental benefit of using hydrogen as a fuel?
It only produces water and does not contribute to global warming.
What is fractional distillation used for?
To separate crude oil into more useful fractions.
What is cracking in the context of hydrocarbons?
A process that breaks up less useful large molecules into more useful smaller molecules.
What prefix denotes 1 carbon in a hydrocarbon?
Meth
What is the general formula of the alkanes?
CnH2n+2
What family of hydrocarbons has at least one carbon to carbon double bond?
Alkenes.
What is the general formula for alkenes?
CnH2n
What defines cycloalkanes?
Carbons are joined in a cyclic manner with no carbon to carbon double bonds.
What indicates that a hydrocarbon is unsaturated?
It has at least one carbon to carbon double bond.
What test can be used to identify unsaturated hydrocarbons?
Add bromine water and shake; if unsaturated, it will decolourise rapidly.
What are monomers?
Small subunits that make up plastics.
What is polymerisation?
The process by which monomers are joined to form a polymer.
What is a thermosetting polymer?
A polymer that cannot be reheated and reset after moulding.
What is a thermoplastic polymer?
A polymer that can be remoulded on heating many times.
What is the property of Polyvinylchloride (PVC)?
Rot proof.
What is the use of PTFE (Teflon)?
Non-stick pans.
What is the environmental issue related to plastics in landfill?
They take around 400 years to disappear.
What is the effect of marine pollution on wildlife?
It can have devastating effects.
True or False: Burning plastics can release carbon monoxide due to a shortage of oxygen.
True.
