[Savan]

If every citizen of the planet would plant a tree tomorrow, how long CO2 concentration in the air would decrease by 1 ppm?
-world population is 7 billion people;
-Each year the tree produces 9 kg O2:
-the Volume of atmosphere = 4.3 * 10²¹ L.

[Arkcon]

We'd like to see your attempt first, like we mentioned in your previous thread :http://www.chemicalforums.com/index.php?topic=84689.msg306857#msg306857

This requirement is part of the Forum Rules{click}

You needed balanced reactions last time, so you should know this problem won't be solvable without them this time.

[Savan]

V CO₂ =  V atm * C CO₂ = 4.3*10²¹ * 10^-6 L CO₂
=> V CO₂ = 4.3*10¹⁵ L CO₂
 1 mole CO₂ ... 22.4 L
 x moles...4.3*10¹⁵ L
=> x=1,92*10¹⁴ moles CO₂

    a                                 9*10³ g
6CO₂ + 6H₂O --> C₆H₁₂O + 6O₂
 6*44g                              6*32g

=> a=12.37 kg CO₂ / tree-year

=> 12.37*10³ / 44 moles = 2,81*10² moles CO₂ =>281 moles CO₂ / tree-year
total number of moles: nCO₂ = 7*10⁹*281 = 1967*10⁹ moles CO₂/year
time/year = 1.9*10¹⁴/1967*10⁹ = 96.5 years ≈ 97 years.

[mikasaur]

I didn't check your actual math but the flow of it looks fine to me.

[Savan]

Thank you!!