How many #"kJ"# are needed to ionize #"100 gram atoms"# of dihydrogen if the ionization energy of hydrogen is #"1312 kJ/mol"#?

1 Answer
Truong-Son N.
Oct 27, 2017

When I looked it up, I got, "the amount of an element whose weight in grams is numerically equal to the atomic weight of the element."

So I figure, since hydrogen as an element is #"H"_2#, the amount of #"H"_2# that has a mass numerically equal to #"1.008 amu"#, the atomic mass of #"H"# atom, is #"0.5 mols"#, since the molar mass of #"H"_2# is #"2.016 g/mol"#.

So, #"100 gram atoms"# of #"H"_2# is #"50 mols"# of #"H"_2#. However, the ionization energy is for #"H"# atom, so I don't think your answer is correct...

If I go through with this (which is nonsense! What about the atomization energy which is not given?), this gives:

#50 cancel("mols H"_2) xx (2 cancel("mols H"))/cancel("1 mol H"_2) xx "1312 kJ"/cancel"mol H"#

#=# #"131200 kJ" = 1.31 xx 10^5 "kJ"#

Hopefully you can see why this definition is obsolete now... it causes confusion for diatomic elements. Again, I don't think your book is correct.

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