For the reaction ? C6H6 + ? O2 → ? CO2 + ? H2O 39.4 grams of C6H6 are allowed to react with 103.4 grams of O2. How much CO2 will be produced by this reaction? Answer in units of grams.

Answer 1

Hello, Tapasiya,

I'm not sure which aspect of this question you'd like help on. I'll go through the overall approach in a summary style, but please let me know if there is something for which you'd like a more thorough explanation.

I believe the equation that balances is:

2C₆H₆ + 15O₂ = 12CO₂ + 6H₂O

Ugly, I know. But water's single oxygen forces us to increase the moles of water so that there are an even number of O atoms, since O only comes in as an even diatomic gas. Then the hydrogens require attention. I usually start with the most complex molecule, which would be the C₆H₆.

Convert the grams of both the O₂ and C₆H₆ to moles by dividing their masses by their molar masses

O₂ = 3.33 moles

C₆H₆ = 0.5051 moles

At first glace, one might think we have more than enough oxygen to consume all the C₆H₆, but we don't. The molar ratio of O₂ to C₆H₆ is (15 moles O₂)/(2 moles C₆H₆) or7.5. We need O₂ to be 7.5 times the moles of C₆H₆ , or 3.788 moles O₂. Oxygen is thus the limiting reagent. All of the oxygen present will consume only 0.431 moles of C₆H₆. (3.23/7.5).

Assuming all 0.431 moles of the C₆H₆ react, we can see that if we multiply that by the molar ratio of CO₂/C₆H₆ , which is (12 moles CO₂/2 moles C₆H₆) or 6, we will find the number of moles of CO₂ produced.

6 (moles CO₂/;moles C₆H₆)*(0.431 moles C₆H₆) = 2.585 moles CO₂

(2.585 moles CO₂)*(44g/mole CO₂) = 113.7 grams CO₂ (114 grams with 3 sig figs)

I hope this helps,

Bob