How Much Carbon from Fossil Fuels and Deforestation Remains in the Atmosphere?

[Maharg]

Homework Statement

The total mass of C contained in all fossil fuels burned from 1750 to 2000 is estimated
as 2.77 x 1014 kg C. The amount of C released as CO2 from agricultural expansion and
deforestation during the same period is estimated as 1.31 x 1014 kg C. The concentration
of CO2 in the atmosphere was 360 ppm in 2000, corresponding to an atmospheric pool
mass of C of 7.74 x 1014 kg C. If the concentration of CO2 in 1750 was 280 ppm,
calculate the % of C from these 2 sources that has stayed in the atmosphere over the 250
years.

Homework Equations

Shown in class how to calculate molecular mass of atmosphere, was 28.96 g/mol

The Attempt at a Solution

I tried calculating molecular mass of atmosphere which is 28.96 g/mol.

Took 360 ppm = 360E-6 multiplied it by 44 g/mol CO2.

I got 0.01584 g/mol then divided this by molecular mass of atmosphere so CO2 is 0.05469%. I'm stuck and don't know how to relate this percent to mass of carbon.

I have also been suggested to use it a proportion so if 7.74E14 kg relates to 360 then 280 ppm CO2 relates to 6.02E14 Kg Carbon, but this doesn't seem right to me.

I just need to understand how ppm CO2 relates to kg C I think

 

[Borek]

What is ppm definition?

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methods

 

[Maharg]

Parts per million. I know how to convert CO2 ppm to atm, but not sure what to do with that number either.

 

[Borek]

You know that given mass of carbon is 360/10⁶ of the total mass of atmosphere - that should be enough to calculate mass of atmosphere. Once you have that, you can easily calculate mass of carbon when it is 280 ppm. But in the end mass of the atmosphere will cancel out and you will be left with exactly the same number as when using proportions

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methods