paper 2

• increassing the pressure means there are more particles per unit volume. this increases the frequency of successful collisions
• increasing the concentration means there are more particles per unit volume . this increases the frequency of successful collisions
• increasing the surface area means there are more particles exposed to collide. this increases the frequency of successful collisions
• increase in temperature makes particles gain energy, so they are faster. this increases the frequency of successful collisions
• a catalyst is a seperate chemical that lowers the activation energy ( minimum amount of energy needed to react) by providing an alternative pathway. this increases the frequency of succesful collisions
• for a reaction to occur between two particles the must collide
• the equilibrium is when the forward rate is equal to the backward rate in a closed system
• the 3 things that can affect the position of equilibrium are temperature, pressure and concentration
• catalysts speed up the forward rate and the backward rate by the same amount
• le chateliers principle states that if a change is made to the conditions of a system, the system will move to restore equilibrium.
• in le chateliers principle if you increase the temperature the equilibruim will follow the endothermic route
• in le chateliers princple if you increase the pressure the equillibruim will move to the side with less molecules
• in le chateliers principle if you increase the concentration the equilibruim will shift to the side with the lower concentration
• the formula for a mean rate of reaction in terms of reactants is quantity of reactant used/time taken
• the 2 possible units for rate of reaction are g/s or cm3/s
• the activation energy is the minimum amount of energy needed to start a reaction
• a pure substance contains only an element or a compound
• to test for hydrogen you need to place a lit splint into the gas and you should hear a squeaky pop
• to test for oxygen place a glowing splint into the gas and the splint should relight
• to test for carbon dioxide use lime water and it should turn cloudy
• to test for chlorine use damp blue litmus paper and it should turn red and then white
• the air pollutant carbon dioxide is made by burning fossil fuelas and deforestation which releases green house gassas which cause global warming and therefore climate change
• the air pollutant methane is released by rice farming and cattle farming which releases greenhouse gases which causes global warming and climate change
• the air pollutant sulphur dioxide is caused when sulfur impurities in coal react with oxygen during combustion which causes repiratory problems and can cause acid rain when it dissolves in water
• the air pollutant nitrogen oxides is produced from combustion st high temperatures where nitrogen and oxygen react in the air which causes repiratory problems and can cause acid rain
• the air pollutant carbon/ soot is when incomplete combustion takes place wich can cause solid particles to block sunlight from reaching earth which causes global dimming
• the air pollutant carbon monoxide is caused during imcomplete combustion which is toxic , colourless, ourderless and can cause death
• some human factors releasing greenhouse gasas are burning fossil fuels, using landfills, agriculture-cattle farming and rice farming, deforestation
• some natural releases of greenhouse gases include solar output, volcanic activity and orbit changes of the earth
• some consequences of climate chage are more frequent floods and droughts, loss of habitats and sea levels rising
• global warming is caused when the earth absorbs short wavelegnth radiation from the suns, warms up and then emits long wavelengths which greenhouse gases then absorb which prevents it from being lost into space. the radiation is then radiated back to earth causing it to warm up even more
• in the uk potable water is from a fresh water source which is then filtered using sand and gravel to get rid of solids, then is sterilised using chlorine and uv light to kill bacteria
• in the middle east potable water is from the sea which is then filtered using sand and gravel to remove solids, the desalination to semove solids using distilation or reverse osmosis which is expensive as it requires a lot of energy. the it is sterilised to kill bacteria using chlorine or uv light
• the waste water treatment procces first solids are removed by screening which is like filtering, then it goes into sedimentation tanks to allow suspended solids to settle, then goes through stones covered in microbes which digest organitc material this is call biological filtration microbes are aerobic. the liquid the settles oin humus tanks and the water is checked and finally the bacteria digest what remains
• the life cycle assessment only asses the environmental impacts
• the limitations of lcas is that it is opinion based, missused and costly
• hydrocarbons are molecules made up of hydrogen and carbon atoms only, they are non-polar
• crude oil is formed from the buried remains of plants and animals that lived millions of years ago and so are non renewable. they can be split into seperate fractions by fractional distilation
• 4.6 bil years ago the earyh was very hot and lots of volcanic activity with little oxygen
• over millions of years the eartyh started to cool and the water vapour condensed to form the ocean