[jguo]

In the chemical reaction notation between sodium and water: 2 Na + 2 H2O --------> 2 NaOH + H2

Why is there a "2" in front of Na, which is sodium?
Can someone also explain this reaction at a chemical level.


Also, reversing a solution and pouring a solvent into a solute have the same effect as pouring the solute in the solvent?

[Hunter2]

Pictures say more as words:

  +  =>  + -

2 + 2 => 2 + -

2 Na + 2 H₂O => 2 NaOH + H-H

2 Na + 2 H₂O => 2 NaOH + H₂

Second question: Yes.

[Borek]

Why is there a "2" in front of Na, which is sodium?

http://www.chembuddy.com/?left=balancing-stoichiometry&right=stoichiometric-calculations

Can someone also explain this reaction at a chemical level.

Not sure what you mean by that.

Also, reversing a solution and pouring a solvent into a solute have the same effect as pouring the solute in the solvent?

In the end - yes, what you call a solvent and what you call a solute is sometimes a matter of convention (50% acetic acid - is it water dissolved in acid, or acid dissolved in water?) When it comes to preparation, order of adding substances to the mixture is often important - for example when diluting concentrated acid you should add the acid to water, not the other way (to not risk splashing).