I really don't get how the chemistry works.

Like, I understand that the "baking soda"  
(I'm not sure the term "sodium bicarbonate" is actually technically correct, so I'll just use the common term)  
[EDIT: this was my first point of confusion]  
has water molecules chemically bound *inside* its crystal structure,  
[no]  
and that heating it breaks those off and converts it to the anhydrous form, "washing soda"  
[no]  
("sodium carbonate" apparently?)  
which is about 10-times stronger of a base.  
(eg of claim (ie "10-times stronger"): [youtube Adam Ragusea's "Ramen orecchiette — easy homemade alkaline noodle soup"](https://www.youtube.com/watch?v=M1n8qc9Jfsk))

The problem is, when I go to make a noodle dough with dry "washing soda",  
I find I need to add it to water and *heat* it first to really get it to dissolve,  
which complicates the process of making a dough  
(especially if you're using eggs, so you need to be careful to get it *cool* again before you mix those in).

So I was wondering if I could just *pre*-dissolve the "washing soda", and just use like a spoonfull of that in each batch of dough, except...

How does that *not* just convert it back into weaker "baking soda"?

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EDIT:  
Okay, so what thought I read about "sodium bicarbonate" being a technically incorrect misname was just completely wrong

https://en.wikipedia.org/wiki/Sodium_bicarbonate#Thermal_decomposition

That is, the thermal decomposition actually *is* changing the molecule itself,  
and not just converting the crystal structure to the anhydrous form?

https://en.wikipedia.org/wiki/Sodium_carbonate

EDIT EDIT:  
I have no idea what I was thinking, where the heck I thought I read that.  
*maybe* I was vaguely remembering that "sodium bicarbonate" (NaHCO3) doesn't actually have double the CO3, but rather, "sodium carbonate" (Na2CO3) has double the Na relative to "sodium bicarbonate"?  
And I *somehow* got that confused into... the thing about "water of hydration/crystallization"??

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Or maybe I should just find some jiǎnshuǐ(碱水 (鹼水)) / kansui(かん水) or something, i dunno...?  
[which is I believe something like 80% potassium carbonate and 20% sodium carbonate dissolved in water (not sure what concentration)]