Energy content of gasoline and hydrogen comparative math question

[courtneywetts]

Yes, you haven't used the final ratio: 70g CO2 corresponds to 1MJ energy.
If 1 gal gasoline releases 133,155 g of CO2, and each 70g CO2 indicates 1MJ of energy, how many MJ for the whole gallon?

When I did this I got 1902.214 MJ. Is this right?

If so how would I go about doing part B?

 

[courtneywetts]

Wait I realized that is only for 1 gallon so I got 28530 MJ

 

[haruspex]

When I did this I got 1902.214 MJ. Is this right?
that is only for 1 gallon so I got 28530 MJ

Right!

If so how would I go about doing part B?

This is much easier. you have 15 gals at 12.8 MJ/m^3.

 

[courtneywetts]

Right!

This is much easier. you have 15 gals at 12.8 MJ/m^3.

I don't understand what this means though? Is this all the information I need?

 

[haruspex]

I don't understand what this means though? Is this all the information I need?

The only other information you need is how to convert US gallons to m³. Look it up.

 

[SteamKing]

Yes. So you have, for burning gasoline:

• 12 atomic masses C corresponds to 44 atomic masses CO2
• 70g CO2 corresponds to 1MJ energy
• 1 gallon gasoline corresponds to 36,315 g C

So how many J energy correspond to 1 gallon gasoline?

This is incorrect. According to the attachment in Post #4, 1 gallon of gasoline has a carbon content of 2421 g, not 36,315 g. The latter figure is for 15 gallons of gasoline.

 

[haruspex]

This is incorrect. According to the attachment in Post #4, 1 gallon of gasoline has a carbon content of 2421 g, not 36,315 g. The latter figure is for 15 gallons of gasoline.

Well spotted - thanks. But fortunately courtneywetts used the right ratio later.