Question

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

Answer 1

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Hopefully you can see why this definition is obsolete now...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.