**Problem**

Analysis of an air sample reveals that it contains 3.5 x 10

^{-6}g/l of carbon monoxide. Express the concentration of carbon monoxide in lb/ft

^{3}.

**Solution**

Two conversions are required, one from grams to pounds using this conversion:

1 lb = 453.6 g

and the other conversion, from liters to cubic feet, using this conversion:

1 ft

^{3}= 28.32 l

The conversion may be set up in this fashion:

3.5 x 10

^{-6}g/l x 1 lb / 453.6 g x 28.32 l / 1 ft

^{3}= 0.22 x 10

^{-6}lb/ft

^{3}

**Answer**

3.5 x 10

^{-6}g/l of carbon monoxide is equal to 0.22 x 10

^{-6}lb/ft

^{3}

or, in scientific notation (standard exponential notation):

3.5 x 10

^{-6}g/l of carbon monoxide is equal to 2.2 x 10

^{-7}lb/ft

^{3}