Chemistry H.
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.

And your trouble with this problem is mainly what?

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

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.