[Auroturtle]

Okay so we had this lab in Chemistry dealing with Baking Soda and finding which of the three possible equations is the correct one:

NaHCO3 (s) -> NaOH (s) + CO2 (g)
2NaHCO3 (s) ->Na2O (s) + 2CO2 (g) + H2O (g)
2NaHCO3 (s) -> Na2CO3 (s) + CO2 (g) + H2O (g)

These are already balanced, as you can see... so let me get to the problem... Our teacher told us to use stoichiomitry to find the correct equation, but I completely ignored her and did something much quicker.

I set up a ratio for each equation comparing the Sodium Bicarbonate to each resulting solid after heating. So it would look like this for each one:

(NaHCO3 / NaOH)
(2NaHCO3 / Na2O)
(2NaHCO3 / Na2CO3)

and the results are as follows when pluggin in the molar masses:

47.6%
36.9%
63.1%

Now what I did was do the same thing, but using the actual experimental results.
The starting baking soda was 0.89g, and after it decomposed, the solid remaining was 0.55g

Now I did the same thing, (0.55g / 0.89g) and got 61.8%

Now, accounting for small errors, this is almost exactly the same to the "perfect" ratio in the third one, which is actually the right answer.

She actually told the entire class that doing this lab without stoichiomitry would be impossible, but since I've completely ignored her directions twice before and gotten a correct answer, I have very little belief what she says...

If anyone actually read this entire thing, please answer and tell me whether this was just a fluke or a way 5x faster than what my teacher did?

[Schrödinger]

You calculated molar ratio.. So actually, what you did, is stoichiometry.

http://en.wikipedia.org/wiki/Stoichiometry

[Natalia]

Yes, you used stoichiometry, just didn't perform the experiment. Your method was indeed very smart for solving this problem, but I doubt that you could do away with just calculations in an "actual experiment"... Because the point is usually to figure out an equation, not to pick over 3 choices!