This is driving me nuts! Please help!?

Question

How many moles of atoms are in one molecule of acetylene?

HOW is the answer: 6.64 E-24???

Answer 1

The book answer is not negative, it has a negative exponent.

A mole is 6.022x10^23 (I'm using this instead of 6.022E^23 because the notation is equivalent)

C2H2 is 4 atoms

4 atoms * (1 mole/ 6.022X10^23 atoms) =

(4/6.022) * 10^-23 moles=

0.6642*10^-23 moles =

6,642 X 10^-24 moles

Answer 2

The point of "a mole" is to represent a large number of molecules, large enough to actually see or work with.  The question wants to know approximately what fraction of a mole one molecule represents.  So yes, you would expect it to be a very small number.

1 molecule C2H2 x (4 atoms / 1 molecule) x (1 mole / 6.02E23 atoms) = 6.64E-24 mol