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General revision- Part 2 (Hydrocarbons (Hydrocarbon = A compound of…
General revision- Part 2
Addition polymers
Addition polymerisation = is a process involving many small, unsaturated monomers combining to form one large polymer molecule. The alkenes ethene and propene are two important feedstocks in the petrochemical industry which can also be used to make addition polymers.
Alkene = any of the series of unsaturated hydrocarbons containing a double bond, including ethylene and propene.
Alkane = any of the series of saturated hydrocarbons including methane, ethane, propane, and higher members.
Polymer = are made up of lots of the same molecule joined together in one long chain. They're what make up plastics.
Alkenens (and reactions)
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2) The C=C Bond means that alkenes have 2 fewer hydrogens compared with alkanes containing the same number of carbon atoms. This makes them unsaturated
3) The C=C double bond can open up to make a single bond, allowing the two carbon atoms to bond with other atoms. This makes alkenes reactive- more reactive than alkanes
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Hydrocarbons
Hydrocarbon = A compound of hydrogen and carbon, such as any of those which are the chief components of petroleum and natural gas.
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- As the length of the carbon chain changes, the properties of the hydrocarbon change
1) The shorter the carbon chain, the properties of the hydrocarbon change
2) Hydrocarbons with shorter carbon chains are also more volatile, i.e they have lower boiling point
3) Also, the shorter the carbon chains, the more flammable the hydrocarbon is
4) The properties of hydrocarbons affect how they're used for fuels. E.g. short chain hydrocarbons with lower boiling points are used as 'bottled gases'- stored under pressure as liquids in bottles
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Le Chatelier's principle
Le Chatelier's principle = is the idea that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract that change
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- Temperature = Our heat of reaction is positive, so this reaction is endothermic. Since this reaction is endothermic, heat is a reactant. By Le Chatelier's principle, increasing the temperature will shift the equilibrium to the right, producing more NO2.
- Pressure = Changing the pressure only affects an equilibrium involving gases
- Concentration = If you change the concentration of either the reactants or the products, the system will no longer be at equilibrium
Isotopes
Isotopes = different forms of the same element, which have the same number of protons but a different number of neutrons
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3) Because many elements can exist as a number of different isotopes, relative formula mass is used instead of mass number when referring to the element as a whole. This is an average mass taking into account the different masses and abundances of all the isotopes that make up the element
Percentage yield
Percentage yield = is the percent ratio of actual yield to the theoretical yield. It is calculated to be the experimental yield divided by theoretical yield multiplied by 100%
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- You never get a 100% yield
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Units and conversions
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- Volume = dm³ x 1000 = cm³
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