Question

The amount of organic carbon stored in sedimentary rocks is about 5 x 10¹⁹ kg of carbon equivalent. How much oxygen would be consumed if ALL of this carbon were extracted and combusted?

Molecular weights: C is 12, molecular oxygen is 32, and carbon dioxide is 44, in equal units.

For comparison, the mass of molecular oxygen (O₂) in the atmosphere is 1.2 x 10¹⁸ kg. Is there sufficient oxygen available to burn all the stored organic carbon in rocks?

Answer 1

Given that

Amount of C = 5 x 10¹⁹ kg

Molecular weights: C is 12, molecular oxygen is 32, and carbon dioxide is 44, in equal units

The balance reaction is as follows:

CO2= CO2

Mole of C= (5 x 10¹⁹ kg *1000 g/1.0 kg )/ 12 g/ mole

= 4.2 x 10²¹ mole C

Number of O2 required=

4.2 x 10²¹ mole C *1/1= 4.2 x 10²¹ mole O2

Amount of O2= 4.2 x 10²¹ mole O2*32 g/ mole

= 1.3*10 x 10²³ g

= 1.3*10 x 10²³ g *1.00 kg/1000 g

= = 1.3*10 x 10²⁰ kg

According to the problem ; For comparison, the mass of molecular oxygen (O₂) in the atmosphere is 1.2 x 10¹⁸ kg.

This amount of oxygen it less than required amount