Help with moles?

[MariamXO]

I was wondering if someone knows any source thats really good at explaining moles. Also if you know how to answer this question please explain how: 5.60 x 10^25 atoms of H = _______ mol of H2O. 

[kw0573]

The individual terms should be fairly intuitive to see. For example the last term is just from definition of Avogadro's number and definition of mol. The hard part is knowing whether you multiply them or divide. So you want mol of water as the final "unit" so you want all the intermediate "units", such as H nuclei, water molecules all to cancel out. 

@Msj ChemYou are absolutely right! Thank you for pointing that out.

 

 

Edited March 20, 2016 by kw0573

[Msj Chem]

You could try my video on moles:

 

 

[Msj Chem]

On March 19, 2016 at 4:44 AM, MariamXO said:

I was wondering if someone knows any source thats really good at explaining moles. Also if you know how to answer this question please explain how: 5.60 x 10^25 atoms of H = _______ mol of H2O. 

One water molecule is made of 1 O atom and 2 H atoms. If you have 5.60 x 10^25 H atoms, you would have 5.60 x 10^25 / 2 = 2.8 x 10^25 water molecules. One mole of water contains 6.02 x 10^23 water molecules. Now you can calculate mol of H2O. 

[Msj Chem]

On March 19, 2016 at 5:13 AM, kw0573 said:

The individual terms should be fairly intuitive to see. For example the last term is just from definition of Avogadro's number and definition of mol. The hard part is knowing whether you multiply them or divide. So you want mol of water as the final "unit" so you want all the intermediate "units", such as H nuclei, water molecules all to cancel out. 

 

 

 

One mole equals 6.02 x 10^23, not x 10 ^26. The answer should be 46.5 mol