Na + H2O -> NaOH + H (or) 2Na + 2H2O -> 2NaOH + H2?

[BigToque]

I'm doing a chem assignment and I can't understand why the correct answer always comes up as (2Na + 2H2O -> 2NaOH + H2).

Are both equations not balanced?

 

[Ionizer86]

Well, hydrogen is a diatomic gas. You can't have just H, it's gotta be H2 (g).

 

[Lonyo]

Well, hydrogen is a diatomic gas. You can't have just H, it's gotta be H2 (g).

This.

It's like you need 2H2 + O2 -> 2H20 instead of H2 + O -> H2O

 

[edro]

I love these threads.
It's like learning chemistry all over again!

 

[PieIsAwesome]

This is why you should memorize diatomic substances.

 

[Tiamat]

Na + H2O -> NaOH + 0.5*H2 is the balanced form.

Thermodynamically, hydrogen exists as a diatomic molecule, therefore the balanced equation must represent that.

Exceptions are reactions which produce ions, but that requires a more in-depth chemistry background than just rudimentary general chemistry.

Also, realize that the "->" incorporates so many steps that you might not be aware of. It includes adding or taking away energy, and intermediate steps which do include single atoms of hydrogen or ionized Na+ and OH- as well as other partials.

As you advance in kinetics and chemistry, you may find that the final step doesn't occur within the time frame of your experiment. There can be many meta-stable steps which you might take advantage of for everyday experiments.

C(diamond) -> C(graphite) is a most simplistic version of what I just mentioned.