# Homework Help: Fun and interesting question

1. Apr 6, 2006

### PhysicsinCalifornia

Hi, I have an assignment from my Chemistry class which is supposed to be done during my Spring break.

The question is to CALCULATE the annual production of CO2(carbon dioxide) in metric tons by all humans in the world from breathing.
The assumptions are:
1. The composition of exhaled breath of average adult is 4.0 percent CO2 by volume.
2. The temperature of the gas exhaled is 25 degrees C at one atmosphere total pressure.
3. The tidal volume of an average adult human is 500 mL or .50 L. The tidal volume is the amount of air that is exhaled during each breath. This is not the total capacity of the lung, which is approximately 5 to 6L depending on many variables.
4. Assume that the average adult takes approximately 22 breaths per minute.
5. The population of the earth is 6.6 x 10^9 humans

I just got this, and I will show my work, but for those who already got the answer, I would like to know what you got to compare with my answer. Thanks

2. Apr 8, 2006

### johny_doe

My answer is roughly 2.75 * 10^12 kg = 2.75 * 10^9 metric tons of CO2 per year.

Tiger (too lazy to register)

3. Apr 8, 2006

### Staff: Mentor

Same here.

4. Apr 10, 2006

### PhysicsinCalifornia

Did you use the equation $$C_8H_{18}(l) + O_2(g) \rightarrow CO_2(g) + H_2O(g)$$?

5. Apr 10, 2006

### Hootenanny

Staff Emeritus
You don't need to use any equations. All the data that is required is given.

-Hoot

6. Apr 10, 2006

### PhysicsinCalifornia

Sorry, I had another question, and that equation dealt with the previous question. I didn't know that I didn't have to use this equation for this problem. In that case, what is the first step to finding how much one person produces CO2 in one breath? I thought that PV=nRT was involved but I don't know anything about consumability. Sorry, it's spring break for me, so my brain shut off this week:zzz: