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jhun1203  
#1 Posted : 16 April 2012 17:05:48(UTC)
Rank: Forum user
jhun1203

I am searching for a formula to be used to calculate carbon dioxide from the emission of vehicle using gasoline. Any reliable source(e.g. book, etc) that I can use please.
Jane Blunt  
#2 Posted : 17 April 2012 07:47:43(UTC)
Rank: Super forum user
Jane Blunt

Basic facts: Petrol is a mixture, nominally octane. The formula for octane is C8H18. 1 litre of petrol weighs between 0.71 and 0.77 kg (depending on precise composition and temperature). All the carbon in petrol is assumed to be converted to CO2. Calculations: The formula mass for octane is 8 x 12 + 18 x 1 = 114g The formula mass for CO2 is 1 x 12 + 2 x 16 = 44g 1 molecule of octane produces 8 molecules carbon dioxide, hence 114g octane produces 8 x 44 = 352 g carbon dioxide. 1 litre has a mass 0.74 kg (the middle figure in the range), hence 0.74 kg petrol will produce 0.74 x (352/114) kg carbon dioxide = 2.3 kg. Looking on the internet using the search terms around 'carbon dioxide emissions petrol' produces a result of 1 litre petrol 2.3 kg CO2 (so the above is spot on) 1 litre diesel produces 2.7 kg CO2 1 litre LPG produces 1.6 kg CO2
jhun1203  
#3 Posted : 17 April 2012 18:31:28(UTC)
Rank: Forum user
jhun1203

Hi Jane, nice formula...few questions....regarding "1 litre of petrol weighs between 0.71 and 0.77 kg (depending on precise composition and temperature)." Where can I get this data? It is standard weight for all the petrol? How about in dubai? I should get this from the petrol station?
JJ Prendergast  
#4 Posted : 17 April 2012 22:15:25(UTC)
Rank: Super forum user
JJ Prendergast

The weight (more correctly mass) will be dependent upon the density. Density = mass/volume The figures quoted are typical for petrol and other hydrocarbons. Available from text books, if you don't want to calculate. The combustion calculation is a standard combustion calculation, using molecular/molar values. Easily looked up in any A level standard chemistry text book
Jane Blunt  
#5 Posted : 18 April 2012 07:36:46(UTC)
Rank: Super forum user
Jane Blunt

jhun1203 wrote:
Hi Jane, nice formula...few questions....regarding "1 litre of petrol weighs between 0.71 and 0.77 kg (depending on precise composition and temperature)." Where can I get this data? It is standard weight for all the petrol? How about in dubai? I should get this from the petrol station?
No, it is a range, due to the variability of the composition of petrol and the temperature. If you want an accurate figure for your own use, measure out a litre of petrol and weigh it. However, this does not necessarily improve the precision of the result since other assumptions have been made in the calculation. We have assumed it is octane. We have assumed all the carbon finishes up as carbon dioxide.
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