What number of molecules of water contains #"0.6 atoms"# of #"H"#? What number of molecules is going to contain a total of #"4.5 atoms"#?

1 Answer
Truong-Son N.
Feb 12, 2018

Well, apparently you really mean fractional atoms!

#a)#

#"0.6 atoms H" xx (1 cancel"mol" "H"_2"O")/(2 cancel"mols" "H") = color(red)"0.3 molecules"# of water... whatever that means.

It then follows that there are supposedly #"0.3 atoms"# of #"O"#, as the number of #"H"# atoms in 1 molecule of #"H"_2"O"# is twice the number of #"O"# atoms.

#b)# #"4.5 atoms H + O" = "3.0 atoms H" + "1.5 atoms O"#... whatever that means.

By knowing that you have #"H"_2"O"#, it follows that the number of #"H"# atoms is twice the number of #"O"# atoms. Therefore, you have #color(red)"1.5 molecules"# of water, since there is one #"O"# for every one #"H"_2"O"#.

Again, this is not physically realistic... atom literally means "indivisible", so you cannot have fractions of an atom.

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