# Chemistry and Science

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carbon dioxide is a "greenhouse" gas in that it absorbs energy from the sun, causing heating of the atmosphere and eventually global warming. carbon dioxide is produced from the combustion of carbon-containing fuels such as coal (mainly carbon), natural gas (mainly CH4), and petroleum (assume to be C8H18). Given the information in the following table, calculate which fuel contributes the least to global warming by calculating the energy obtained per gram of carbon dioxide produced.

Given

Coal - Carbon = 32kJ/g
Natural gas - CH4 = 49kJ/g
Petroleum - C8H18 = 48kJ/g

I am not sure where to start, with an equation?
or convert 1 g of C to moles and then find the kJ/mol?

• Chemistry and Science - ,

I'll give you an example using CH4.
CH4 + 2O2 ==> CO2 + 2H2O
I'm a little confused by the table: I assume it means 49 kJ heat released by 1 g CH4. So we want 1 g CO2; how much CH4 will we need to produce 1 g CO2.
1 g CO2 x (1 mol/44g) = about 0.023 mols. You can go through and clean up the estimates. From the equation, that means we must start with 0.023 mol CH4 and that is 0.023mol x (16g/mol) = 0.36g CH4. That means we must burn 0.36 g CH4 to obtain 1 g C. The energy produced will be 49 kJ/gCH4 x 0.36g CH4 = ??kJ energy.
The others are done the same way but they may not be as simple since the equations may not be 1:1 as CH4 and CO2 are.

• Chemistry and Science - ,

i think althought that generally carbon from coal with 32kj/g from natural gas and petroleum very lesser produces energy and global warming.
good luck...