Doubling the concentration of BRS 2 part?

[Saintnovakai]

The alk part is very likely to have precipitation in it. We have designed two parts to generally be close to saturated, and I would not assume you can make the alk part a lot more concentrated.

I knew I wasn't all stupid. Lol

 

[MnFish1]

Sort of curious eh? I'm more inclined to trust Randy's warnings than my single observation, even if I did watch it mix up clear. Now I'm curious what drives precipitation of something that was able to dissolve initially.



See my post about this, doubling the volume is not a trivial task in this case.

I saw it - and I'm sorry - but - it also doesnt mean you can violate the laws of chemistry. .... I agree with @Randy Holmes-Farley

 

[Dkeller_nc]

Sort of curious eh? I'm more inclined to trust Randy's warnings than my single observation, even if I did watch it mix up clear. Now I'm curious what drives precipitation of something that was able to dissolve initially.

It is possible to make solutions of ionic compounds where the substance in question is actually above the equilibrium concentration - this is called supersaturation. In such solutions, adding a nucleation site for crystallization results in the near instant formation of precipitation throughout the solution. However, making solutions like this requires certain rather special conditions, one of which is highly pure solution components and extremely clean containers.

What people more often observe is the effect of temperature on solubility of a particular compound, which for most (but not all) substances goes up with increasing temperature. Stirring a solution on a stir plate will increase the temperature of the solution above ambient, however slightly. So you can get a solution that's stable at the temperature that it's at on the stir plate, but it will precipitate as the solution slowly cools to the ambient temperature. Also, most residential dwellings experience changes in ambient temperature throughout the day and over weeks/months as the weather changes. So if you're at or near the saturation point of a substance, the solution may mix up clear with no precipitation at a particular time of day or on a particular day, only to have the solution precipitate as the ambient temperature goes down at another time of day or another particular day.

One note about this - if you want to make up considerably more concentrated solutions, you can use either a straight sodium hydroxide solution as the alkalinity part, or some mixture of sodium hydroxide and sodium carbonate/bicarbonate. I believe that Randy & Jim Welsh have published such solutions fairly recently on Reef 2 Reef.

 

[MnFish1]

It is possible to make solutions of ionic compounds where the substance in question is actually above the equilibrium concentration - this is called supersaturation. In such solutions, adding a nucleation site for crystallization results in the near instant formation of precipitation throughout the solution. However, making solutions like this requires certain rather special conditions, one of which is highly pure solution components and extremely clean containers.

What people more often observe is the effect of temperature on solubility of a particular compound, which for most (but not all) substances goes up with increasing temperature. Stirring a solution on a stir plate will increase the temperature of the solution above ambient, however slightly. So you can get a solution that's stable at the temperature that it's at on the stir plate, but it will precipitate as the solution slowly cools to the ambient temperature. Also, most residential dwellings experience changes in ambient temperature throughout the day and over weeks/months as the weather changes. So if you're at or near the saturation point of a substance, the solution may mix up clear with no precipitation at a particular time of day or on a particular day, only to have the solution precipitate as the ambient temperature goes down at another time of day or another particular day.

One note about this - if you want to make up considerably more concentrated solutions, you can use either a straight sodium hydroxide solution as the alkalinity part, or some mixture of sodium hydroxide and sodium carbonate/bicarbonate. I believe that Randy & Jim Welsh have published such solutions fairly recently on Reef 2 Reef.

That said if the alkalinity solution is near saturation (as it supposedly is?) -it wouldn't be easy to double the concentration even with a stir bar, or?

 

[Dkeller_nc]

That said if the alkalinity solution is near saturation (as it supposedly is?) -it wouldn't be easy to double the concentration even with a stir bar, or?

Yep, true enough. From looking at data on wikipedia, it does appear that Na2CO3's saturation concentration is a strong function of temperature. So depending on what temperature that Randy chose for a saturation amount, I suppose that it is possible that the OP could roughly double the concentration if the temperature was different enough. From wikipedia, anhydrous Na2CO3's saturation at 15 deg C is 164 g/L, while at 27.8 deg C, the saturation concentration is 341 g/L.

 

[Dkeller_nc]

Just as an addendum to this discussion, I translated BRS's instructions to a weight-to-volume concentration:

BRS instructions - 2.333 cups to the gallon of soda ash (Na2CO3), which is 552 mL (cm^3)
Density of Na2CO3 - 2.54 g/cm^3
Average solid content of a powder - 0.6 volume fraction

Therefore, there's 2.54 g/cm^3 * 552 cm^3 * 0.6 = 841 grams. There's 3.78 liters in a gallon, so the BRS concentration is 841g/1gal*(1gal/3.78L) = 222.5 grams/L

Comparing that to wikipedia's notes about the solubility of Na2CO3 in water, 222g/L would be somewhat over the solubility limit at 15 deg C, and somewhat under the solubility limit at 28 deg C.

 

[MnFish1]

Just as an addendum to this discussion, I translated BRS's instructions to a weight-to-volume concentration:

BRS instructions - 2.333 cups to the gallon of soda ash (Na2CO3), which is 552 mL (cm^3)
Density of Na2CO3 - 2.54 g/cm^3
Average solid content of a powder - 0.6 volume fraction

Therefore, there's 2.54 g/cm^3 * 552 cm^3 * 0.6 = 841 grams. There's 3.78 liters in a gallon, so the BRS concentration is 841g/1gal*(1gal/3.78L) = 222.5 grams/L

Comparing that to wikipedia's notes about the solubility of Na2CO3 in water, 222g/L would be somewhat over the solubility limit at 15 deg C, and somewhat under the solubility limit at 28 deg C.

I did the same thing - except I used a calculator (designed to convert cups of sodium carbonate to grams) - 2.33 cups= 1395 gm/3.78 =approx 370 gm/l or 37 gm/100 ml. (https://www.aqua-calc.com/calculate/volume-to-weight). Solubility is 25gm/l at 25 c So if your method underestimates some - and mine overestimates - it seems like its pretty close to saturated (i.e. not possible to double the concentration?)

 

[Randy Holmes-Farley]

well the OP has stated that it already mixed up fine soo...

Sure, reinvent the wheel. [emoji23]

We already invented it once or twice, but folks always think it’s a new idea to make it more concentrated. Many folks have problems making and storing solutions a lot more concentrated, which is THE ONLY reason I designed it at the concentration it is. Note that it is a constant complaint that the ESV B-ionic concentrate often has precipitate in it and needs to be warmed to dissolve it.

Yes, you can likely make it somewhat more concentrated, if that’s useful. The solubility is easy to look up. But if you want it a lot more concentrated then a hydroxide version is a better bet.

 

[Dkeller_nc]

I did the same thing - except I used a calculator (designed to convert cups of sodium carbonate to grams) - 2.33 cups= 1395 gm/3.78 =approx 370 gm/l or 37 gm/100 ml. (https://www.aqua-calc.com/calculate/volume-to-weight). Solubility is 25gm/l at 25 c So if your method underestimates some - and mine overestimates - it seems like its pretty close to saturated (i.e. not possible to double the concentration?)

That's kind of interesting. The only difference between our calculations (other than a small bit of rounding error) is the inclusion/exclusion of the void factor inherent in measuring granular/powdered materials. I'd always assumed that reported value of density for a solid is for a solid block, with no void space. So if you have an aliquot of material that's in the form of perfect spheres, the amount of empty space is 0.33. Since a granular/powdered material generally isn't in the form of perfect spheres, one generally uses a void space ratio of 0.4.

Perhaps I'm incorrect about the assumption of density being reported as a solid block - I'll have to look into it.