The number of carbon atoms in the pencil mark is 3X1017 atoms of carbon
The atomic weight of carbon is 12.01 amu, so 12.01 g of carbon contains 6.022X1023 atoms. Thus equation: 12.01 g carbon/ 6.022 X 1023 atoms (3X1017 atoms) (12.01 g carbon/ 6.022X1023 atoms)
- the atoms cancel out
(3X1017) (12.01g carbon/6.022X1023)
divide and multiply
= 6x10-6g carbon
The mass of this pencil mark in grams is 6x10-6g carbon
