Posted by Jennifer on .
Assume that the nucleus of the fluorine atom is a sphere with a radius of 5 x 10 ^ 13 cm. Calculate the density of matter in the fluorine nucleus in grams/cm^3. Now convert your answer to tons per cubic centimeter, knowing that there are 454 grams in one pound.

Chemistry H. 
DrBob222,
And your trouble with this problem is mainly what?

Chemistry H. 
Jennifer,
I don't understand how to set up the conversion problem.. Or what exactly it's asking

Chemistry H. 
DrBob222,
The volume of a sphere is (4/3)*pi*r^3. The problem gives radius; substitute and solvge for volume in cc.
The problem doesn't give you the mass of a F nucleus but you know the atomic mass is 19.0 grams for a mol so 1 atom has a mass of 19.0/6.02E23) = ?g
mass = volume x density
Substitute mass and volume from above and solve for density in g/cc.
(grams/454) converts to lbs and (lbs/2000) converts to tons.
You make conversions this way.
Given x factor = new unit
Say you want to convert 500 g to lbs. The factor is 1 lb = 454 g.
500 g x factor = lbs.
500 x (1 lb/454) = 1.1 lbs.
Note that there are two ways to use the factor. One is 1 lb/454 g and the other is 454g/1 lb. How do you know which to use. In this example you want to use 1 lb/454g because this way the grams (the unit we don't want to keep) cancel (g in the numerator cancels with g in the denominator of the factor) and the unit we want to change to (lbs) is left alone.