Sciencemadness Discussion Board

Need som help

Mahiasss - 17-12-2003 at 01:41

There has been a fire in a house where NaHCO3 was stored and the police is worried about the nature.

1. 2NaHCO3 -> 2Na + H2 + 2C + 3O2
2. 2NaHCO3 -> Na2O + H20 + 2CO2
3. 2NaHCO3 -> Na2CO3 + H2O + CO2
4. NaHCO3 -> NaOH + CO2
5. 4NaHCO3 -> 4Na + 2H20 +O2 + 4CO2

I'm pretty sure reaction #3 is the correct one, but my job is to find out which one with help from an experiment. How would I do that?

Theoretic - 17-12-2003 at 01:57

You don't need an experiment. Reaction 3 is the one, if the fire was a hot one then the Na2CO3 produced could have decomposed to Na2O and CO2.
I you do want an experiment, just heat NaHCO3! Place a cold object when anything starts coming off. Condensed steam will tell you number 3 is the one.

I have a lingering suspicion this is a homework question... :D:D:D

Mahiasss - 17-12-2003 at 02:06

You're right, this is a homework. Tnx anyway ;)

We must make an experiment to find out which one. So I just heat it up and the condensed steam will tell me that it is reaction #3?

[Edited on 17-12-2003 by Mahiasss]

Marvin - 17-12-2003 at 06:00

Heat up the sodium bicarbonate until it stops decomposing. See if you can condense any water from the gas coming off as Theoretic suggested but this does not tell you which if you get water coming off.

Add excess acid to the residue, if it fizzes lead the gas into lime water. If you get a preciptate, it can only be one of those equations.

unionised - 17-12-2003 at 13:25

The powder in dry- powder fire extinguishers is NaHCO3.
Perhaps the police should have asked the fire service.

Acid Test - 7-1-2004 at 14:37

But the fire started from adding the sodium to the water.The fire was attempted to be put out by the NaHCO3.
Since this was added the outcome reaction is unknown.

That is why he is asking others to do the experiments.He is in a risk of getting busted and needs to know which reaction is going to produce the substance he wants.He can't name it because he will get busted.

Acid Test - 8-1-2004 at 08:29

How do you know it is thermal.
It could be caused by several unknowns.

-Exposure to light,ultraviolet,or infrared
-exposure to moisture
-exposure to to a reacting temperature