I understand that the correct equation is supposed to be the first one where sodium carbonate was produced. However, through calculations using the ratio between reactant and solid product, my experiment showed that equation 2 where sodium oxide was produced is supposed to be correct.
So now you're faced with a decision. You can either:
- Massage the result of your experiment until it comes up with the answer you think is "supposed" to be correct.
- Report the result of your experiment as it actually happened.
If you take the first route, I'm sure we can come up with some convincing explanations. Maybe your starting sodium bicarbonate contained water (so it wasn't 100% pure) and that water was driven off in the heating. Maybe you spilled some as you put it in the crucible. Maybe some of the mixture in the crucible splashed out during the reaction. Maybe you read the scale wrong. Maybe there is another reaction that also happens, perhaps involving the air, or the crucible, or the gas from the bunsen burner.
But I think it would be much more honest to report your result as it actually happened. Your data supports the hypothesis that the sodium bicarbonate decomposed to sodium oxide. In fact, the agreement with that hypothesis is quite strong, and the agreement with the supposedly correct hypothesis is terrible. It could be that this is due to an error you made... or maybe the stupid sodium bicarbonate didn't get the memo that, according to the teacher (or the text or Wikipedia or whatever), it was supposed to decompose to sodium carbonate, so it just went ahead and decomposed all the way to sodium oxide.
I realize you're probably worried about being marked down on your lab report because you came to the "wrong" conclusion. Any decent teacher, though, would give you much more credit for correctly interpreting your data and coming to a conclusion based on the data, even if it's wrong, than for massaging your data to support a preconceived hypothesis.