How many atoms are in 131.97 liters of water vapor at STP?

1 Answer
Jun 3, 2017

Well the molar volume at "STP", is 22.4*L*mol^-1. (Check this value out with your syllabus...........)

Explanation:

And so we take the quotient to get the number of moles.............

"Number of moles"=(131.97*L)/(22.4*L*mol^-1)=5.8921*mol,

Note that this is dimensionally consistent as the L cancels out, and 1/(mol^-1)=1/(1/(mol))=mol as required.

Now we know that in ONE MOLE, there are "Avogadro's Number" of particles, i.e. 6.0221xx10^23*mol^-1

And thus......................."number of particles" = 6.0221xx10^23*mol^-1xx5.8921*mol=

3.5479xx10^24 "individual gas particles........"

And since an individual gas particles CONTAINS THREE ATOMS, i.e. H_2O(g), there are................

3.5479xx10^24*"molecules"xx3*"atoms"*"molecule"^-1

=1.0644xx10^25*"atoms".

How many oxygen atoms, and how many hydrogen atoms?