Chemists, mathematicians and wanna be's

hkgar · 04/30/2018, 02:07 PM

Randy's recipe 1 calls for 596 grams baking soda to make 1 gallon. There are 3785 ml in a gallon of water. That would be 37.85 g/100ml water?

This article states that the solubility of baking soda in water is 9.3 g 100ml., or 352 grams. (9.3*37.85)

What am I missing?

Also,
I just weighed 1 cup of baking soda and came up with 264 g equaling 660 g per 2.5 cups, the amount in volume Randy's recipe calls for.

And just for further confusion: Self-Rising Flour: 1 cup = 4 ounces = 113 grams. Baking powder: 1 teaspoon = 4 grams. Baking soda: 1/2teaspoon = 3 grams. Butter: 1/2 cup =1 stick = 4 ounces = 113 grams from a google search.

teaspoons in 1 cup 48 therefore 96 1/2 teaspoons and at 3 g per 1/2 tsp. we get 720 g in 2.5 cups.

Vinny Kreyling · 04/30/2018, 06:17 PM

Which weighs more?
A pound of feathers or a pound of beef?
The same but different volumes.

bertoni · 04/30/2018, 10:36 PM

Recipe 1 is baked baking soda, which is sodium carbonate. I have forgotten how much it weights after baking, but noticeably less, and sodium carbonate is much more soluble in water. 660 g is very close to 596 g for our purposes. We'd have to check into your scale's accuracy limits to do much more computation. How has it been calibrated?

hkgar · 05/01/2018, 04:43 AM

Quote:

Originally Posted by bertoni

Recipe 1 is baked baking soda, which is sodium carbonate. I have forgotten how much it weights after baking, but noticeably less, and sodium carbonate is much more soluble in water. 660 g is very close to 596 g for our purposes. We'd have to check into your scale's accuracy limits to do much more computation. How has it been calibrated?

105.9888 g/mol Sodium carbonate weight, but I have no idea what a mol is?

My scale can't be calibrated but 10 nickles weigh 50 g on it.

I baked 594 grams for 1 hour at 200 f and mixed into 1 gallon of water and a significant amount still was not dissolved.

Hooligan · 05/01/2018, 06:55 AM

Quote:

Originally Posted by hkgar

Randy's recipe 1 calls for 596 grams baking soda to make 1 gallon. There are 3785 ml in a gallon of water. That would be 37.85 g/100ml water?

I believe you made an arithmetic mistake here. I get 15.75g/100ml water. ((596/3785) * 100).

Quote:

Originally Posted by hkgar

This article states that the solubility of baking soda in water is 9.3 g 100ml.

This article supports that figure and also tells me that if you raise the water temperature to 60C you'd be able to dissolve 16.5g (a bit more than we need) in that 100ml. Not sure if this is acceptable for your purposes...

Quote:

Originally Posted by hkgar

And just for further confusion: Self-Rising Flour: 1 cup = 4 ounces = 113 grams. Baking powder: 1 teaspoon = 4 grams. Baking soda: 1/2teaspoon = 3 grams. Butter: 1/2 cup =1 stick = 4 ounces = 113 grams from a google search.

I wouldn't worry too much about conversions in an article about baking - I'd guess they'd be approximate at best.

Quote:

Originally Posted by hkgar

105.9888 g/mol Sodium carbonate weight, but I have no idea what a mol is?

My scale can't be calibrated but 10 nickles weigh 50 g on it.

I baked 594 grams for 1 hour at 200 f and mixed into 1 gallon of water and a significant amount still was not dissolved.

Sounds like your scale is accurate.

Baking soda is NOT sodium carbonate, it is sodium bicarbonate. But for this discussion molar concentration isn't important so let's not worry about this.

As stated in the above-referenced article, if your water was at room temperature, it makes sense that it would not all dissolve...

Hope this helps!

Mr. Wiggles · 05/03/2018, 07:28 PM

I agree with Hooligan above. Also don't forget when the baking soda is baked it turns to sodium carbonate. Baking the recommended 594 g of bicarbonate turns it into about 335g of sodium carbonate. The carbonate has a solubility of about 22g/100mL. The 335g of carbonate in a gallon is about 8-9 g/100mL, which is well within the room temperature solubility of sodium carbonate.

Long story short, if you try to dissolve 600g of bicarbonate in a gallon you are over the solubility and it will not all stay dissolved at room temperature. Baking the bicarbonate turns it into carbonate which should be easily soluble at room temperature.

bertoni · 05/03/2018, 10:15 PM

The scale seems okay. I agree that you can dissolve the baking soda by heating. That will convert it to sodium carbonate (effectively), which is why it works. Technically, some of the sodium bicarbonate will dissolve and heating will drive off carbon dioxide, allowing more sodium bicarbonate to dissolve. Do you actually want recipe 2, the low-pH version? That is about half as concentrated, for reasons we've discussed.

04/30/2018, 02:07 PM	#1
hkgar Registered Member Join Date: Oct 2002 Location: Dewitt MI Posts: 5,051	Chemists, mathematicians and wanna be's Randy's recipe 1 calls for 596 grams baking soda to make 1 gallon. There are 3785 ml in a gallon of water. That would be 37.85 g/100ml water? This article states that the solubility of baking soda in water is 9.3 g 100ml., or 352 grams. (9.337.85) What am I missing? Also, I just weighed 1 cup of baking soda and came up with 264 g equaling 660 g per 2.5 cups, the amount in volume Randy's recipe calls for. And just for further confusion: Self-Rising Flour: 1 cup = 4 ounces = 113 grams. Baking powder: 1 teaspoon = 4 grams. Baking soda: 1/2teaspoon = 3 grams.* Butter: 1/2 cup =1 stick = 4 ounces = 113 grams from a google search. teaspoons in 1 cup 48 therefore 96 1/2 teaspoons and at 3 g per 1/2 tsp. we get 720 g in 2.5 cups. __________________ Gary 180 gallon, 40 gallon sump, 3 250 W MH + 4 80W ATI T5's, MTC MVX 36 Skimmer, Apex controller Aquamaxx T-3 CaRx Current Tank Info: A 2 Barred Rabbitfish, Red Head Salon, Yellow/Purple, McMaster Fairy, Possum, 2 Leopard Wrasses, Kole, & Atlantic Blue Tangs, 2 Percula Clown, 3 PJ and 1 Banggai Cardinalfish , Swallowtail, Bellus and Coral Beauty Angels Last edited by hkgar; 04/30/2018 at 02:54 PM.

04/30/2018, 06:17 PM	#2
Vinny Kreyling Registered Member Join Date: Nov 2002 Location: Miller Place, NY Posts: 7,206	Which weighs more? A pound of feathers or a pound of beef? The same but different volumes. __________________ 250 gallon mixed reef, 2 Reefbreeder's Photon V 2, Deepwater BLDC 12, DAS EX-3 Skimmer, MTC mini cal, 2-3/4" Sea Swirls, Aquacontroller & 6 Tunze pumps.

04/30/2018, 10:36 PM	#3
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	Recipe 1 is baked baking soda, which is sodium carbonate. I have forgotten how much it weights after baking, but noticeably less, and sodium carbonate is much more soluble in water. 660 g is very close to 596 g for our purposes. We'd have to check into your scale's accuracy limits to do much more computation. How has it been calibrated? __________________ Jonathan Bertoni

05/03/2018, 10:15 PM	#7
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	The scale seems okay. I agree that you can dissolve the baking soda by heating. That will convert it to sodium carbonate (effectively), which is why it works. Technically, some of the sodium bicarbonate will dissolve and heating will drive off carbon dioxide, allowing more sodium bicarbonate to dissolve. Do you actually want recipe 2, the low-pH version? That is about half as concentrated, for reasons we've discussed. __________________ Jonathan Bertoni

05/03/2018, 07:28 PM	#6
Mr. Wiggles Registered Member Join Date: Jun 2010 Location: Chapel Hill, NC Posts: 197	I agree with Hooligan above. Also don't forget when the baking soda is baked it turns to sodium carbonate. Baking the recommended 594 g of bicarbonate turns it into about 335g of sodium carbonate. The carbonate has a solubility of about 22g/100mL. The 335g of carbonate in a gallon is about 8-9 g/100mL, which is well within the room temperature solubility of sodium carbonate. Long story short, if you try to dissolve 600g of bicarbonate in a gallon you are over the solubility and it will not all stay dissolved at room temperature. Baking the bicarbonate turns it into carbonate which should be easily soluble at room temperature.