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Author Topic: Sodium Bicarbonate  (Read 9802 times)

Offline Steve Vai

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Sodium Bicarbonate
« on: 02/09/2005 13:18:15 »
i have a packet of sodium bicarbonate i saved from eternal decay at the back of the cupboard, is there anything interesting i can do with it? other than reacting with vinegar in bottles (i think).


"Turkeys killed my family" - Chip, 02/09/2005, 12:49


 

Offline Simmer

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Re: Sodium Bicarbonate
« Reply #1 on: 02/09/2005 20:10:16 »
Well you could make some soda bread :)

Apart from trivial applications, such as cooking, cleaning and heartburn, sodium bicarbonate is for producing lots of gas (CO2) quickly when mixed with acids.  I've seen plastic bottle rockets and volcanoes (with some surfactant)but there are probably as many uses as there are forum members! :D
 

Offline Ultima

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Re: Sodium Bicarbonate
« Reply #2 on: 02/09/2005 22:08:26 »
Inflating balloons is quite fun, although it doesn't work all that well.

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Offline daveshorts

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Re: Sodium Bicarbonate
« Reply #3 on: 03/09/2005 11:06:26 »
Put some lemon juice in a flim cannister and then add some bicarb, and put the lid on quick - if you get a good cannister it will make a good pop- we ahve broken several fish tanks that we use to contain the explosion this way so please don't sue me if you get lemon juice in your eye...
 

Offline Steve Vai

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Re: Sodium Bicarbonate
« Reply #4 on: 03/09/2005 13:34:29 »
cool, thanks for that!

how big would the build up of pressure be? in theory would it be possible to put bicarb of soda in a soluble capsule, drop it into some form of container, seal it really tight and leave it to go bang? how big a bang would that make, and would the concentration/strength of the acid used change it drastically?

"Turkeys killed my family" - Chip, 02/09/2005, 12:49
 

Offline Simmer

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Re: Sodium Bicarbonate
« Reply #5 on: 03/09/2005 17:23:23 »
I don't think the strength of the acid matters too much, as someone pointed out it reacts quite vigorously with citric acid, so long as you have enough of it.  

As to how much pressure, I think you get one mole of CO2 (~22 L at STP, IIRC) for each mole of bicarbonate (84 g) so with this quantity in a 1L container you'd get about 20 atmospheres (300 psi or 2000 kPa), quite a big bang assuming your container could almost handle it!

Of course you've got the complication of adding the acid while being a safe distance away but if you want to avoid that you could just heat the container to above 50 C (eg chuck it on a bonfire and run like hell!)
 

Offline Steve Vai

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Re: Sodium Bicarbonate
« Reply #6 on: 03/09/2005 18:18:26 »
cool, thanks for that

btw, could you tell me how you worked out the pressure and moles to weight etc, were going to go onto it at school soon, and my teacher is getting overloaded with questions me n chip ask her lol

"Turkeys killed my family" - Chip, 02/09/2005, 12:49
« Last Edit: 03/09/2005 18:18:50 by Steve Vai »
 

Offline Steve Vai

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Re: Sodium Bicarbonate
« Reply #7 on: 03/09/2005 19:49:44 »
i have a method of doing it

put the bicarb of soda in a tissue, twist it shut, make sure it will fit through the bottle neck

it acts as a rudimentary delay, and if you use a big enough tissue you can leave it wedged in the top before you close it

shake and run

anotehr quick question for the original reply, whats a surfactant? lol

"Turkeys killed my family" - Chip, 02/09/2005, 12:49
 

Offline Simmer

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Re: Sodium Bicarbonate
« Reply #8 on: 04/09/2005 00:38:20 »
Please ignore the "surfactant" remark, that was just me being pretentious (and inaccurate!) :)  What I really meant was a good foaming detergent, like washing-up liquid!

As for the pressure calculation:

A mole of a substance can be defined as its formula weight in grams (stricly speaking it's the weight of the same number of molecules as in 12 grams of carbon 12, 6.023 X 10^23, but life's to short for that stuff!).  

The formula weight of sodium bicarbonate is the sum of the atomic weights of one sodium, one hydrogen, one carbon and three oxygens (approximately 23 + 1 + 12 + 48 = 84) which is where I got the 84 grams from.

When reacted with an acid, one molecule of sodium bicarbonate produces one molecule of carbon dioxide therefore one mole of the bicarbonate will produce 1 mole of carbon dioxide.

One mole of an ideal gas (a gas in which all molecular collisions are elastic and there are no intermolecular forces)at standard temeperature and pressure (STP - 0 degrees C and one atmosphere pressure)would occupy a volume of 22.4 L (PV=nRT).  That's a pretty good approximation for most gases, which is where I got the 20 L from.

Obviously if you put the same amount of gas (1 mole) in a twentieth of the volume (1L), the pressure is twenty times greater (20 atm or about 300 psi or about 2000 kPa).

So there we are, not nearly as clever as I wanted people to think but probably roughly right :D
 

Offline neilep

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Re: Sodium Bicarbonate
« Reply #9 on: 04/09/2005 04:19:41 »
quote:
Originally posted by daveshorts

Put some lemon juice in a flim cannister and then add some bicarb, and put the lid on quick - if you get a good cannister it will make a good pop- we ahve broken several fish tanks that we use to contain the explosion this way so please don't sue me if you get lemon juice in your eye...



Will it be safer to have the bicarb in the cannister first ?...then add the juice  ?....I want to try :)

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Offline Steve Vai

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Re: Sodium Bicarbonate
« Reply #10 on: 04/09/2005 11:17:06 »
thanks for the moles thing, i get most of it, we'll undoubtedly get a shortened version in chemistry this year lol

thanks

alex

"Turkeys killed my family" - Chip, 02/09/2005, 12:49
 

Offline chip

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Re: Sodium Bicarbonate
« Reply #11 on: 04/09/2005 17:35:33 »
This may sound nasty and i would not openly indorse it but if you make some soda bread and feed it to pidgeons i have heard they explode. I dont know whether they go bang or whether they just inflate and keel over but it could be interesting (more so to the biologist)

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Offline Simmer

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Re: Sodium Bicarbonate
« Reply #12 on: 04/09/2005 18:34:55 »
Might work, even after cooking the bread contains sodium carbonate, but would be completely unacceptable and messy. [:(!]  

Remember there is an ethical dimension to science these days.  Much has been written on the subject (http://www.sgr.org.uk/) but basicially it boils down to; you're not allowed to destroy the world (except by accident) and the only animals you are allowed to torture are squirrels.
 

Offline Steve Vai

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Re: Sodium Bicarbonate
« Reply #13 on: 04/09/2005 18:41:02 »
lol, yeh, if you have a pest problem with pidgeons its probably more efficient to shoot them anyway

why squirrels may i ask? lol

"Turkeys killed my family" - Chip, 02/09/2005, 12:49
 

Offline Simmer

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Re: Sodium Bicarbonate
« Reply #14 on: 04/09/2005 20:43:47 »
Squirrels are evil [}:)]

That's a considered judgement based on objective weighing of the evidence, by the way, and has nothing to do with the little bleeders digging up my plants!

Soda bread wouldn't work on squirrels, however.  Unlike pigeons they are quite capable of belching (and indeed all other forms of uncivilised self expression).
 

Offline entropy

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Re: Sodium Bicarbonate
« Reply #15 on: 16/09/2005 01:30:55 »
make some crack cocaine
 

Offline Simmer

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Re: Sodium Bicarbonate
« Reply #16 on: 16/09/2005 18:57:24 »
I doubt if that would get the job done :(  Squirrels are high as kites most of the time anyway, one way or another.  Besides a lot of them are mafia drug dealers and pretty much used to it.
 

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Re: Sodium Bicarbonate
« Reply #16 on: 16/09/2005 18:57:24 »

 

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