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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: michaelt817 on August 29, 2010, 07:57:10 PM

Title: Mass percent and density question?
Post by: michaelt817 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!

Title: Re: Mass percent and density question?
Post by: MrTeo on August 30, 2010, 02:30:59 AM

What does ppm mean?

Title: Re: Mass percent and density question?
Post by: michaelt817 on September 01, 2010, 06:37:47 PM

parts per million

Title: Re: Mass percent and density question?
Post by: cswarth 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