Combustion of ethanol Q (1 Viewer)

[mtsmahia]

Is the increase in atmospheric carbon dioxide has been linked to the burning of fossil fuels. The combustion of octane produces 1.554*10^7 kJ of energy per tonne off carbon dioxide produced.
SNL has been proposed as a more environmentally sound source of energy. The heat of combustion of ethanol is 1367 kJ mol^-1. The energy produced per tonne of carbon dioxide from the combustion of ethanol is ?

The answer is 1.553 * 10^7 kJ

can someone please understand how this was determined ?

Thanks

 

[js992]

Write out your equation for combustion of ethanol

C2H5OH + 3O2 ==> 2CO2 + 3H2O

1 tonne of co2
= 1,000,000 grams

Divide by molar mass of CO2 to find how many moles of CO2 = 1 tonne

1000 000/ 44.01
= 22722.10861 moles

For every 2 moles of CO2 produced, 1 mole of ethanol was combusted.

So
22722.10861/2 moles of ethanol combusted
= 11361.05431 moles of ethanol.

The heat of combustion of ethanol is 1367 kj / mol
Since you have 11361.05431 moles
energy released is 11361.05431 x 1367
= 1.553 x 10^7 kJ

 

[mtsmahia]

Write out your equation for combustion of ethanol

C2H5OH + 3O2 ==> 2CO2 + 3H2O

1 tonne of co2
= 1,000,000 grams

Divide by molar mass of CO2 to find how many moles of CO2 = 1 tonne

1000 000/ 44.01
= 22722.10861 moles

For every 2 moles of CO2 produced, 1 mole of ethanol was combusted.

So
22722.10861/2 moles of ethanol combusted
= 11361.05431 moles of ethanol.

The heat of combustion of ethanol is 1367 kj / mol
Since you have 11361.05431 moles
energy released is 11361.05431 x 1367
= 1.553 x 10^7 kJ

OH !! i misread the Q :angry:
THANKS FOR THE HELP