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# Chemical reaction equation for a blend of Ethanol and Petrol watch

1. Hi,

I am struggling with a question that requires the chemical reaction of a combustion of a blend of Ethanol and Petrol. Below are the chemical equations of the cumbustion of Petrol and Ethanol on their own and I need to know the equation of the blend, containing %50 Ethanol and %50 Petrol.

Ethanol: C2H5OH + 3O2 -----> 2CO2 + 3H2O

Petrol: C8H18 + 12 1/2O2 -----> 8CO2 + 9H2O
2. (Original post by mech_eng)
Hi,

I am struggling with a question that requires the chemical reaction of a combustion of a blend of Ethanol and Petrol. Below are the chemical equations of the cumbustion of Petrol and Ethanol on their own and I need to know the equation of the blend, containing %50 Ethanol and %50 Petrol.

Ethanol: C2H5OH + 3O2 -----> 2CO2 + 3H2O

Petrol: C8H18 + 12 1/2O2 -----> 8CO2 + 9H2O
50% by mass or volume?
3. never seen a question like this.
I would solve like empirical formula problem
if 50% by molecular weight then
50/(24+5+16+1)= 1.08 mol

50/((8*12) +18) = 0.44mol 0.44/0.44=1

1.08/0.44= 2.45

double mols to get 2 mols of petrol and 5 mols of ethanol

make equation 5C8H18+ 2C2H5OH +O2 -------> CO2 + H2O

balance it 5C8H18+ 2C2H5OH + 67 1/2O2 -------> 44CO2 + 51H2O

i maybe very very wrong!!!!!!

you may just have to make into one equation.
4. (Original post by charco)
50% by mass or volume?
By the mass
5. (Original post by mech_eng)
By the mass
If it is by mass, then all you need to do is convert this into a molar ratio.
Then you can have two simultaneous basic combustion reactions (stoichiometrically adjusted according to the molar ratios). The actual mechanism may well not be so simplistic, but the end products will almost certainly be the individual combustion products.

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