# How to calculate atoms of *each* element in a compound

I am trying to do the following exercise in a chemistry workbook. I have searched over internet but I couldn't find or understand it.

How many atoms of each element are found in:

• 5 moles $$\ce{H2SO4}$$

Now the only confusing thing for me is the 5 moles.

For example lets take $$\ce{H2}$$ element

so n=N/Na --> n × Na = N (number of atoms)

2 × 1gr/mol H = 2 moles H x 5 moles in the compound = 10 moles

10 moles $$\ce{H2}$$ × 6.02 × $$10^{23}$$ = 60.2 × $$10^{23}$$ atoms

Or do I do like this?

5 moles $$\ce{H2}$$ × 6.02 × $$10^{23}$$ = 30.1 × $$10^{23}$$ atoms

• There is no such element as H2. May 21 '17 at 10:38

Think of the mole as a SI prefix, like 'kilo' or 'mega'. If you have 5k $\ce{H2SO4}$ molecules, you will have 10k hydrogen atoms, not 5k. Just as 'kilo' means '1000', a mole means $6.02 \cdot 10^{23}$ of something.