MilkTheFrog
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Basic question about forming Rochelle Salt
Part of my AS Level Physics coursework involves giving a talk on the properties of a material. Now rather than just make a powerpoint and mumble over
it i thought i'd be a little bit interesting and (well, try to) do a demonstration. Going by a certain makemag video i saw a while ago i decided to
try to show and explain (that looks like it's going to be the tricky bit  ) the
piezoelectric properties of Potassium sodium tartrate.
Now i ordered some Potassium bitartrate and Sodium bicarbonate from the bay, they arrived today. This is where the question comes into it - every
guide i've found on the net says to use Sodium Carbonate, or if you can't get it to bake Sodium Bicarbonate. However after a bit of searching on this
forum i heard the suggestion to just use straight up bicarb. Is that possible? Are there any disadvantages to doing so?
Many thanks! 
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ScienceSquirrel
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Best way to do it is to follow a recipe.
http://seawhy.com/xlroch.html
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Adas
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What is the use of Rochelle salt?
Rest In Pieces!
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ScienceSquirrel
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http://en.wikipedia.org/wiki/Rochelle_salt
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MilkTheFrog
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Yeah, that's one of the ones i was looking at. So you're saying it's not possible to just substitute the Sodium Carbonate with Sodium Bicarbonate?
[Edited on 17-2-2012 by MilkTheFrog]
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ScienceSquirrel
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Baking the sodium bicarbonate is easy and the sodium carbonate is a stronger and a lot more soluble base.
If you do not have much chemistry experience following the recipe is the easy way to go.
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Magpie
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Here's a thread with my pictures of Rochelle salt, which grew quite quickly:
http://www.sciencemadness.org/talk/viewthread.php?tid=6376#p...
In another thread I post the recipe:
"Weighed out 39g Cream of Tartar and added to 49 mL of water. Placed slurry in 250mL beaker in water bath using Corelle bowl on stirrer-hotplate.
Heated until bath water at simmer. Added washing soda (Na2CO3) carefully with spatula until no more bubbles formed. Filtered hot solution into
evaporating dish. ~2 hours later 7 large crystals of Rochelle salt had formed."
The single most important condition for a successful synthesis is good mixing - Nicodem
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