#11 Balancing Reactions Part 1

Question

___Na     +          ___H₂O →              ___NaOH +         ___H₂

_{Please answer and explain how you got it.}

Answer 1

Hi Katrina! The balanced equation would look like this:

2 Na + 2 H₂O ---> 2 NaOH + 1 H₂

So the coefficients from left to right are 2, 2, 2, 1.

My advice is to start with the most complicated compound/thing in the equation and put 1 mole with it, and see if that works out. So what I first did is identified that NaOH looks to be the most complicated thing in this equation, but when I put 1 mol in front of it, I saw that the entire right side of the equation had 3 Hydrogen, and the left only had 2. From there, I decided to put 2 moles in front of NaOH, which when looking at the right side of the equation I had 2 moles total of Na and so the left also needed to have 2 moles of Na, so I put 2 moles in front of Na on the left side.

This also meant that I had 2 moles of Oxygen on the right side, and needed 2 moles of Oxygen on the left, so I added 2 moles in front of H₂O to get there.

And finally, the left side of the equation had 4 moles total of Hydrogen, so the right also needed 4 moles total of Hydrogen, which is why I only put 1 mol in front of H₂. It seemed to have worked out perfectly when I checked my work.

I hope that made sense! I tried to explain it as simply as possible. It just takes a lot of time and practice to get good at these equations. What I also do is keep a count of how many of each element/molecule/thing are on each side of the equation, which makes it a lot easier when checking work and stuff like that. Please feel free to reach out with any additional questions or help needed!

Answer 2

Hello, Katrina,

Balancing chemical equations requires some art and patience. The first thing to remember is that the equation can be read as single molecules. 

We start with the basic equation:

___Na     +          ___H₂O →              ___NaOH +         ___H₂

Start with one molecule of the most complex one, in this case NaOH: 

___Na     +          ___H₂O →              _1_NaOH +         ___H₂

The Conservation of Matter law tells us we must have the same number of atoms on both sides. Since we set NaOH to "1," we need to add it's elements from the reactant side. One sodium is needed, so add 1 to Na. We also need one O and 1 H, so let's also add a "1" to H₂O.

_1_Na     +          _1_H₂O →              _1_NaOH +         ___H₂

Now we have more than enough for one NaOH molecule. There is one H from the H₂O not used by the NaOH, so it will go to the H_2.. We need 2 H, since hydrogen is a diatomic molecule. We only have 1, so far. So let's use it by assigning "1/2" for the H₂ coefficient:

_1_Na     +          _1_H₂O →              _1_NaOH +         _1/2_H₂

Check to confirm that all the elements from the reactants are accounted for in the products.

Reactants Products

Na 1 1

H 2 2

O 1 1

So the equation is now balanced. But we can't have 1/2 of a molecule. We need to double all the coefficients to bring 1/2H₂ to 1H₂.

_2_Na     +          _2_H₂O →              _2_NaOH +         _1_H₂

The elements are still balanced:

Reactants Products

Na 2 2

H 4 4

O 2 2

AND we don't have fractions of a molecule.

I have a more detailed analysis of how to balance equations in Wyzant's Resources page:

https://www.wyzant.com/resources/files/729420/balancing_chemical_equations

I hope this helps,

Bob