This is just showing you how to use a mole of anything (in this case carbon atoms).
Equation
Set up a proportion for solution.
[tex]\dfrac{12.01 \text{grams}}{6.02*10^{23} \text{ atoms C}} = \dfrac{x}{3.48 * 10^{25} \text{ atom C}}[/tex]
Notice that the two units that are the same will eventually cancel out and you will be left with grams.
Solution
Multiply both sides by 3.48 * 10^25
[tex]\dfrac{3.48*10^{25} \text{ atoms C}*12.01\text{ grams}}{6.02*10^{23} \text{ atoms C}} = \text{x}[/tex]
Cancel out the powers and units that can be cancelled.
3.48*10 * 12.01 / 6.02 = x
Solve for x
x = 69.42 grams
