Substituting sodium bicarbonate for sodium carbonate to produce H2. Will it still work?
The reactions with sodium carbonate being used:
1) Na2CO3 --> 2Na + CO3 in the water
2) CO3 + H2O --> HCO3 + OH
3) 2Al + 12OH --> 2AlO3.3H2O + 3H2
Obviously, this is a rather slow process. The only problem is I don't HAVE any sodium carbonate, but I do have plenty of sodium bicarbonate. If I substitute sodium bicarbonate for sodium carbonate will the process still work?
Answer:
You can easily make sodium carbonate by putting sodium bicarbonate in a stovetop-safe dish and heating it at high heat. When the temperature is high enough, and you stir it, the sodium bicarbonate powder will "bubble" off CO2. When this reaction stops, you will have sodium carbonate. Keep it in an airtight container, as it will slowly revert to sodium bicarbonate by absorbing CO2 from the air.
No it won't - the sodium carbonate is used as a source of base and a buffer here, and bicarbonate is not basic enough.
Do you have sodium hydroxide? You can use equal molar amounts of bicarbonate and hydroxide (look at the right side of eq. 2)
The key reaction for producing the hydrogen is #3 in your list, where you need the hydroxide ion (OH-) as one of your reactants, which you get from reaction #2 in converting carbonate (CO3--) to bicarbonate (HCO3-). In other words, substituting sodium bicarbonate for sodium carbonate won't work very well; you need a stronger alkali.
Michael P: I was hesitant to suggest using sodium hydroxide (lye) because it is dangerous stuff to work with. However, if NaOH is available, just use it instead of the sodium carbonate.
By the way, a reaction similar to this takes place when you put Drano down the sink.
Well I don't know why Kelani got two thumb downs, because he's right. Heating sodium bicarbonate decomposes it to sodium carbonate, carbon dioxide and water vapor. Under household conditions, you cannot further decompose sodium carbonate.
That being said, your reaction will proceed much faster with NaOH. I've done it with NaOH. I even (foolishly) ignited the hydrogen that evolved. It made a nice popping sound. I only used a few grams though.
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