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.a) Estimate in tons the average total amount of carbon dioxide in the earth atm

ID: 283678 • Letter: #

Question

.a) Estimate in tons the average total amount of carbon dioxide in the earth atmosphere. For this purpose assume that the total air molecules in the atmosphere is about 1.5x1020 moles. Average concentration of carbon dioxide in the earth atmosphere is 400 ppm.

b) Take the year 2011 and estimate the yearly increase of carbon dioxide in the earth atmosphere due to fuel use as a percentage of the total amount present. Convert this to increase in the ppm level. (Emission in 2011 is= 31.342*10^9 tonnes/year)

c) Compare the increase in the concentration of carbon dioxide in ppm calculated in part (b) to the actual figure. If there is a discrepancy give possible explanations. Hint: The carbon dioxide level in the atmosphere is a result of many competing processes, such as removal by photosynthesis, release by microorganisms, emission from fuel combustion, change in tropical land use, ocean uptake, forest regrowth, and carbon dioxide fertilization.

Thank you

Explanation / Answer

a)

Total air molecules=1.5x1020

concentration of carbon dioxide = 400ppm

Average molar mass of dry air = 29.97gm/mol

so in the atmosphere,1.5x1020 moles = 29.97*1.5x1020 gm = 44.95x1020gm

concentration of carbon dioxide = 400ppm = 0.4gm/kg

So total concentration of carbon dioxide in gram =17.98x1017gm = 17.98x1011ton

b)

Carbon dioxide emission =31.342x109tonnes/year

=31.342x1015gm/year

total mass of the atmosphere = 44.95x1020gm

So total Carbon dioxide concentration in the atmosphere = 31.342x1015gm/year/44.95x1020gm

= 0.697/100000 =0.00695gm/kg per year

= 6.97ppm per year

c)

There is an increase in the concentration of carbon dioxide.

There are different reasons for the increase in Carbondioxide concentration. Main factors are fossil fuel combustin, ocean acidification, deforestation etc.