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Topic: Mass percent and density question?  (Read 7683 times)

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Offline michaelt817

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Mass percent and density question?
« on: August 29, 2010, 07:57:10 PM »
The legal limit for human exposure to carbon monoxide in the workplace is 35 ppm. Assuming that the density of air is 1.3g/L, how many grams of carbon monoxide are in 1.0 L of air at the maximum allowable concentration.

Not sure where to start... Any tips would be greatly appreciated!
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Offline MrTeo

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Re: Mass percent and density question?
« Reply #1 on: August 30, 2010, 02:30:59 AM »
What does ppm mean?
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Offline michaelt817

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Re: Mass percent and density question?
« Reply #2 on: September 01, 2010, 06:37:47 PM »
parts per million
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Offline cswarth

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Re: Mass percent and density question?
« Reply #3 on: September 01, 2010, 07:37:27 PM »
I think even I can answer this one....

Assuming they measure ppm as a function of mass (and not volume) then it's simple.
You want t get how may grams CO are permissible in a liter of air.  They tell you how much a liter of air weighs (1.3G/L) and they tell you how much of that can be CO by weight (35/1000000).

You can use unit analysis to make sure the answer makes sense.

(Liters of air) x (grams of air)/(liter of air) x (grams CO)/(grams of air) = grams of CO


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