jamit
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bicarbonate to carbonate
I am currently converting food grade sodium bicarbonate to sodium carbonate by heating it in the oven at boil for about 3 hrs. Is that long enough?
How can you tell when all the bicarbonate has been converted to carbonate?
And what is the chemical grade of the sodium carbonate after conversion from bicarbonate? Is it reagent grade, lab grade, or what?
I want to use sodium carbonate as a primary standard to standardize other acids and bases.
Also, is there a way to test for the presence of bicarbonate or carbonate? I tried adding pottery grade sodium carbonate to HCL and it fizzed alot
and the same thing happened with a solution of bicarbonate, so adding acids doesn't help to distinguish the two chemicals. There's got to be another
way. Any suggestions? thanks.
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arkoma
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suggest mebbe weighing before and after? your losing an atom of hydrogen. bicarb is supposed to change to carbonate at 50c
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woelen
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Heating at boil? You mean 100 C? That is not enough, decomposition then is slow and incomplete. I would heat it to at least 200 C for a few hours. At
200 C I expect you to get a decently pure product (assuming that your starting product is pure). If you want to use the material for standardizing
other acids, then store it in a very well sealed bottle to assure that it does not absorb water from the air. The latter would cause weighing errors
which cannot be corrected for if you do not know the precise amount of absorbed water.
The only practical way I can think of for testing maxes of Na2CO3 and NaHCO3 is to measure the amount of CO2 formed from a known amount of solid and
excess acid. This, however, is not an accurate measurement. It can give you a rough indication of the ratio of NaHCO3 to Na2CO3, but when the chemical
is quite pure already (e.g. at the order of 95% of one of them, then it will be hard to determine the precise amount of the other).
I expect that with your home made Na2CO3 you will get an accuracy not better than a few percent uncertainty, but I think that for most of your
applications that will be sufficient. Keep in mind that this only works accurately with strong acids. Standardizing weak acids like acetic acid with
sodium carbonate will be very inaccurate, due to the lack of sharp transition points.
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jamit
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Thank you guys for such a quick reply, much to think about.
I will try weighing before and after...and thanks Woelen... you're always reliable and helpful in your replies. I'm so glad there's guys like you
around this forum.
Again, thanks.
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violet sin
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@ woelen, I think perhaps jamit meant broil, as "in the oven" was used. regardless the lowest temp on a lot of ovens is like 150'F on the "warm"
setting. real cooking starts at 200'F on mine, but it also has the warm setting as stated. I do as arkoma said and weigh it before and after. done
on steady weight even after more heating.
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jamit
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thanks "violet sin", that's exactly what I meant to say, "broil" not "boil". At broil its 400F.
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prof_genius
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You can find Sodium Carbonate in stores sold as Washing Soda. I found that the brand in the Netherlands is quite pure.
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woelen
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I also
learnt something new. English is not my native language and I did not know the term "at broil". Usually, ovens over here do not have such indications,
we have a dial on them with temperatures in degrees Centigrade (e.g. from 80 C to 250 C or so).
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jamit
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here's in the US, you can buy it from pottery stores, but I'm sure it not reagent grade... maybe at most lab grade.
I thought I try another route, so I decided on making sodium carbonate from sodium bicarbonate which I believe is food grade and therefore quite pure.
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aga
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Your English is better than many English people i have met !
To Broil = To Grill / cook under a Grill
It is an old term and is not used in modern spoken English.
Perhaps it is still in use in US English.
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hyfalcon
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http://householdproducts.nlm.nih.gov/cgi-bin/household/brand...
This is what I use.
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sasan
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I think it is very easy and safe to make sodium carbonate if you use sodium hydrogen carbonate and sodium hydroxide:NaHCO3(aq) + NaOH(aq) <--->
Na2CO3(aq) + H2O(aq) 
Any ideas and questions?
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Pyro
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you can buy it in europe for about 3eur/kg. it must be close to pharma grade as it suggests soaking your feet in it
all above information is intellectual property of Pyro.  |
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arkoma
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Quote: Originally posted by aga  |
Your English is better than many English people i have met !
To Broil = To Grill / cook under a Grill
It is an old term and is not used in modern spoken English.
Perhaps it is still in use in US English. |
Yes, it is. Every oven I've ever seen has a "Broil" setting. Electric ones have an element in the very top that only comes on at broil, and gas ones
have a pull out drawer in bottom.
I ALSO learned something about my native tongue LOL
Typical US oven knob:
"We believe the knowledge and cultural heritage of mankind should be accessible to all people around the world, regardless of their wealth, social
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aga
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It may be a sign of a decline in literacy in the UK that most ovens i have seen recently have Pictures instead of words ...
http://www.shutterstock.com/pic-87168826/stock-photo-oven-pr...
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Texium
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Wow, that's very cryptic! Not sure what the ones with the spikes on the oven ceiling are supposed to represent. And yeah, my oven has a broil setting
on the knob, and the toaster oven has a broil button. I've never really thought of it as being an odd thing. Little oddities of culture are
everywhere!
Also, I found my sodium carbonate at the hardware store as pool pH booster. It claims 99% purity (doubtful) and seems to be anhydrous. If I remember
correctly it was $6 for a 2lb container.
[Edited on 6-25-2014 by zts16]
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aga
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the Spikes are the Grill (Broiler)
One row of spikes = half power
Spikes with a line = full power
With a propeller = fan assisted
The temperature is usually a second digital control knob/buttons.
The Icons on the right are for the top and bottom oven elements
Edit:
The light bulb icon is to get the oven to give you an Idea.
The snowflake icon is what you use for attempting to dehydrate aluminium sulphate.
[Edited on 25-6-2014 by aga]
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DraconicAcid
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It's probably not literacy so much as small market- the company making the knobs also wants to be able to sell them to France, Poland, Sweden, the
Netherlands, Germany...
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Texium
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Wish mine had a setting like that. Must come in
handy sometimes on long boring afternoons. Well, if the oven has any good ideas that is!
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unionised
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I love the idea that there's someone named Aga talking about ovens.
http://en.wikipedia.org/wiki/AGA_cooker
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Pyro
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the pictograms are simple, the more expensive ovens put pictograms on the dial to make the whole thing look more simple and less cluttery
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valeg96
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In Italy is sold as "SODA SOLVAY" by Solvay, and is 99.8%, costs 2.8€/kg in supermarkets and 1.8€/kg in bulk. I may be repetitive but you should
definitely buy it. Heating NaHCO3 is way more expensive.
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Zyklon-A
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I decompose sodium bicarbonate in a stainless steel pan on the stove. I can convert 500 grams to carbonate in just 15 minutes, I think you'll find
this to be a much easier, and faster method.
[EDIT] Just remember to stir often.
[Edited on 28-6-2014 by Zyklon-A]
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Amos
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For all of you that are more interested in the definition of the term broil, it is important to note that it differs from other cooking methods in an
oven by the fact that broiling is done by bombarding food with infrared rays rather than surrounding the food with hot air. This makes whatever is
being cooked more likely to cook on the top and develop a char, and to be less cooked on the inside. As a sidenote, broiling is probably much less
effective than baking in order to convert baking soda to sodium carbonate, as all parts are not receiving the same amount of heat. The steel pan
sounds the best to me, as you're treating the sodium bicarbonate with much higher temperatures, and also driving off more of the ambient water as a
result.
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Ascaridole
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To be used as a primary standard you need to heat your sodium carbonate to 270ºC (518ºF) and cool in a desiccator. The decomposition of bicarbonate
to carbonate is also not 100% efficient at lower temperatures.
Also carbonate needs boiling near the end point and can be fussy if your not careful with indicator choice and solution concentration.
Ascaridole, the masked bandit of chemistry!
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