[Rachel492480]

OK, I've done this problem a million times and I keep getting it wrong. My professor won't show me how to work out the problem, and instead keeps hinting at what the answer is. Chemistry isn't my best subject AT ALL, so hinting at what the answer is doesn't help me at all.

So, how many atoms of P are in 5 moles of P4O10?

I thought it was:

(6.023 * 1023 atoms) * (5 mol) = (3.0115 * 1024)
  ---------------       
    (1 mol)

(3.0115 * 1024 atoms) * 28.57%  = 8.6043 *1023 atoms

Which is apparently wrong.

Then, Yahoo! Answers said something like this:

5 moles of P4O10 * 4 P atoms= 20 moles of P

(20 moles) * (6.023 * 10^23atoms/mole) = 1.2046 *10^25 atoms.

Which doesn't make any sense to me at all. And then my teacher said something like I had the general IDEA of how to answer the problem (which I totally don't) but that he insisted I write out the problem so the units work out. Which, I don't really know how to do. I understand how to work out units and cancel stuff out, but I just don't understand the whole concept of this problem or the way to work this particular problem out at all. So, could someone please show me a very detailed step-by-step process on how to figure out this problem? I have quite a few problems on my homework that are very similar to this one and I have no idea how to solve them. You can even solve a made up problem if you don't want to give me the answer to my homework, I just a blueprint to work with here.

Thank you so much!

[Rachel492480]

Those numbers are meant to have exponents attatched.

ex: 6.023*10^23

[Evaldas]

There are 5 x 6.02 x 10²³ molecules of P₄O₁₀ in 5 mol.
There are four P atoms in a single molecule of P₄O₁₀.

[Borek]

Mole is just an overgrown dozen. 12 objects in a dozen, 6.2x10²³ objects in a mole.

Imagine you have have a dozen P₄O₁₀ molecules. Each contains 4 atoms of P, so in total you have 12*4=48 atoms of P.

Now imagine you have a mole of molecules.

[Rachel492480]

So, 5 moles of P4O10 means that I have (5) * (6.023*10^23) molecules.

And then I multiply that number by 4.

Like if I had 4 dozen eggs and in each dozen, there were 4 brown eggs I would have:

4 * 12 * 4

Is that right?

So I write

6.023 *10^23 molecules  * 5 moles  *  4 atoms of P
----------------------     ---------        -------------
1 mole                               1                 1 molecule of P4O10



Is that it? 

[Borek]

Wasn't that hard.