chemistry paper 2

• catalyst

  these change the rate of a chemical reaction but are not used in the reaction they provide a different reaction pathway where reactants do not require as much energy to react when they collide
• enzymes

  they are biological catalysts
• collision theory

  chemical reactions can only occur when reacting particles collide with each other with sufficient energy
• activation energy

  the minimum amount of energy colliding particles in a reaction need in order to react
• temperatures effect on the rate of reaction

  the higher the temperature the quicker the rate of reaction
• concentrations effect on the rate of reaction

  the higher the concentration the quicker the rate of reaction
• surface areas effect on the rate of reaction

  the larger the surface area of a reactant solid the quicker the rate of reaction
• pressure (of gases) effect on the rate of reaction

  when gases react the higher the pressure upon them the quicker the rate of reaction
• le chatelier’s principles

  when a system experiences a disturbance it will respond to restore a new equilibrium state
• changing concentration

  if the concentration of a reactant is increased more products will be formed
• changing temperature

  if the temperature of a system are equilibrium is increased…

  exothermic reaction = products decrease

  endothermic reaction = products increase
• changing pressure

  for a gaseous system at equilibrium…

  pressure increase = equilibrium position shifts to the side of the equation with the smaller number of molecules

  pressure decrease = equilibrium position shifts to the side of the equation with the larger number of molecules
• crude oil

  finite resource that consists of mainly plankton that was buried in the mud, it is the remains of ancient bio mass
• hydrocarbons

  they make up the majority of the compounds in crude oil and most of them are called alkanes
• alkanes to alkenes

  long chain alkanes are cracked into short chain alkenes
• alkenes

  they are hydrocarbons with a double bond
• properties of alkenes

  they are more reactive than alkanes an reacts with bromine water bromine water changes from orange to colourless in the presence of alkenes
• cracking

  the process of breaking down long chain hydrocarbons into smaller chains these smaller chains are more useful
• catalyst cracking

  a method of cracking where the heavy fraction is heated until vaporised after vaporisation the vapour is passed over a hot catalyst forming smaller more useful hydrocarbons
• steam cracking

  method of cracking where the heavy fraction is heated until vaporised after vaporisation the vapour is mixed with steam and heated to a high temperature forming smaller more useful hydrocarbons
• alkenes and uses as polymers

  they are used to produce polymers and also used as the starting material of many other chemicals such as alcohol plastics and detergents
• hydrocarbon chains in oil

  hydrocarbon chains in crude oil come in lots of different lengths
• hydrocarbon chains boiling points

  the boiling points of the chains depend on its length. During fractional distillation they boil in separate at different temperatures due to this
• fractions

  the hydrocarbons in crude oil can be split into fractions. Each fraction contains molecules with a similar number of carbon atoms in them
• using fraction

  fractions can be processed to produce fuels and feedstock for the petrochemical industry
• condensation polymerisation

  this involves monomers with 2 functional groups. they join together and usually lose small molecules such as water
• fermentation

  ethanol is produced from fermentation
• alkene reactions

  alkenes react with oxygen in the same way as other hydrocarbons just with a smoky flame due to incomplete combustion
• pure substance

  a substance made of a single element or compound not mixed with any other substance
• formulation

  this is a mixture that has been designed as a useful product. They are made by mixing chemicals that have a particular purpose in careful quantities
• hydrogen test

  burning splint

  positive results = popping sound
• oxygen test

  glowing splint

  positive result = re lights the splint
• chlorine test

  damp litmus paper 

  positive result = bleaches the paper white
• carbon dioxide test

  lime water 

  positive result = goes cloudy
• carbon monoxide

  toxic, colourless and odourless gas which is not easily detected and can kill
• sulphur dioxide and oxides of nitrogen

  causes respiratory problems in humans and acid rain which can affect the environment
• particulates

  causes global dimming and health problems in humans
• global climate change effects

  rising sea level, extreme weather events, changes in the amount of rainfall, changes to distribution of wildlife species
• the greenhouse effect

  radiation from the sun enters the earths atmosphere and reflects off of the earth. Some of this radiation is re radiated back by the atmosphere to the earth which warms up the global temperature
• carbon dioxide

  human activities that increase carbon dioxide levels include burning fossil fuels and deforestation