How would you balance: Na + H2O --> NaOH + H2?

2 Answers
Nov 16, 2015

2Na + 2H_2O -> 2NaOH +H_2

Explanation:

You have to count the number of atoms in both sides of the reaction to be equal, to make it a little easier you can make a list. So in the equation Na+H_2O->NaOH+H_2, there are
1-Na-1
2-H-3
1-O-1
So you multiply NaOH and H2O by 2, so you have 4 hydrogens in both sides, and then multiply Na by 2 to be equal to the NaOH you previously multiplied.

Nov 12, 2016

2"Na"_ ((s)) + 2"H"_ 2"O"_ ((l)) -> 2"NaOH"_ ((aq)) + "H"_ (2(g))

Explanation:

I'm assuming that you're supposed to balance this chemical equation by inspection. You could also balance it by using oxidation numbers, but I don't think that you're supposed to go that route here.

So, your unbalanced chemical equation looks like this

"Na"_ ((s)) + "H"_ 2"O"_ ((l)) -> "NaOH"_ ((aq)) + "H"_ (2(g))

Notice that you have 3 atoms of hydrogen on the products' side, but only 2 on the reactants' side.

Here is where a little experience can come in handy. You can multiply the sodium hydroxide by 2 to get a total of 4 atoms of hydrogen on the products' side.

This will allow you to simply double the number of water molecules to get 4 atoms of hydrogen on the reactants' side.

So you now have

"Na"_ ((s)) + color(blue)(2)"H"_ 2"O"_ ((l)) -> color(blue)(2)"NaOH"_ ((aq)) + "H"_ (2(g))

Balance the atoms of sodium by multiplying sodium metal by 2

2"Na"_ ((s)) + color(blue)(2)"H"_ 2"O"_ ((l)) -> color(blue)(2)"NaOH"_ ((aq)) + "H"_ (2(g))

And now check to see if the atoms of oxygen are balanced. You have 2 atoms of hydrogen on the reactants' side and 2 on the products' side, which means that the equation is balanced.