combustion of alkanes Flashcards
what do combustion reactions gve out?
a large amount of heat
what type of enthalpy does combustion have ?
negative
what increases the heat given out in combusion of alkanes?
more carbons present
do fuel store a large amount of energy in a small weight ?why dpes it matter ?
yes ,this means they release alot a heat
when doe complete combustion of alkanes occur ?
when their is plenty of oxygen
when does incomplete combustion of alkanes occur ?
limited supply of o2
what is the equation for complete combustion ?
alkane(g) + oxygen(g) -> water(l) + carbon dioxide(g)
what is the eqaution for incompleter combustion ?
alkane(g) +o2(g) + CO (g) +H2O(l)
how does combusion of alkanes pollute the atmosphere?
all hydrocarbon based fuela derived from crude oil may produce pollution product when they burn .
what is the chemical test for carbon dioxide ?
bubble gas through lime water water =makes white particulate
what is the chemical test for water ?
anhydrous copper sulphate is white so turns blue or chlorine paper turns from blue to pink
what is the physical test for water ?
boil and see if it boils at 100 degrees then water
why does lime water make a white participate when mixed with carbon dioxide ?
lime water is calcium hydroxide soloution . Calcium hydroxide soloutio and carbon dioxide makes calcium carbonate (lime stone )
how is carbon monoxide formed ?
lack of oxygen so carbon dioxide can’t be formed
why does carbon monoxide have a negative impact ?
carbon monoxide is toxic -can replace oxygen in blood and lead to poisoning by oxygen deficiency
how is sodium dioxide formed ?
composition of coal and crude oil depends on where it is mixed and drills .usually only contain small qauntities of sulfur commpounds .which can be organic (CH3SH) or inorganic (H2S , FeS)
when heated in air they oxidise
what is the negative impact of sodium dioxide?
toxic
air pollution
how are nitrogen oxides produced ?
N2O and NO2 is produced when nitrogen is oxidised .high tem in car engine cause nitrogen and oxygen in air to react
what is the equation for nitrogen oxides to be produced ?
N2+O2->2NO
what is the negative impact of the product of nitrogen oxides ?
acid rain -4NO2+O2+2H2O->6HNO3
how are unburnt hydrocarbons produced ?
fuels pass through car engine without combusting and is releases at petrol filling stations
what negative impacts do unburnt hydrocarbons have
global dimming
respitory irritant
may cause health problems for those with breathing problems or asthma
what is particulate matter ?
carbon /soot
how is particulate matter formed ?
incomplete combustion of carbon containing fuel
what is the negative impact of particulate matter ?
global dimming
respitory irritant
what does a catalytic converter do ?
converts toxic harmful gases into less harmful gases
what structure is a catlytic converter ?
honeycomb containing transition meta;s
give the eqaution for catalytic converters ?
co+O2->CO2 + NOx
how can sulfur dioxide be removed ?
its acidic do flue gases by reacting with an alklai
what is used when removing sulfur dioxide by flue gases ?
calcium carbonate and calcium oxide mixed with water to make a slurry
what is done with the slurry ?
sprayed onto flue gases
what happens when the slurry and surfur dioxide react ?
reacts with alkaline slurry and produces solid waste product ,calcium sulphite
give the eqautions for removal of sulfur dioxide by flue gases ?
CaO(s)+ 2H2O(l) + SO2(g) -> CaSO3(s)+ 2H2O+2H2O (l)
CaCO3(s)+ 2H2O(l) +SO2(g) ->CaSO3(s)+ 2H2O(l)+ CO2( g)
