# DIVISION/MULTIPLICATION WORD PROBLEM?? Find concentration of CO2 given particles per million and number of particles in air?

The concentration of CO2 in the air is 410 ppm. A breath of air contains approximately 1.2 × 1022 particles of air. How many of these particles are CO2?

How would go about solving this?

I have the following:

x ppm = (x molecules / 1 x 10^6 particles of air)

Can I just set it up like this?:

( 410 CO2 / 1 x 10^6 particles of air) * (x CO2 / 1.2 x 10^22 particles of air) ??

It's been a long time since I've had to do math, so some reinforcement/corrections would be really nice!

### 1 Answer

Relevance

- hcbiochemLv 71 month agoFavourite answer
Yes, you can do this as a proportion where:

410/1X10^6 = x / 1.2X10^22

Cross multiplying gives:

4.92X10^24 = 1X10^6 x

x = 4.92X10^18 CO2 molecules

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