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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

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

Therefore, the first approach gives the correct answer, but I don't understand what you mean by 1gr/mol. Grams are out of the picture here.

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  • $\begingroup$ Ok really thanks. Appriciate it man. gr/mol That was a stupid mistake of mine $\endgroup$ May 21 '17 at 10:30

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