Measuring Calcium Chloride

[h22lude]

Of course! I always forget vinegar. I'll try that, thanks

 

[h22lude]

When I first made my solution, the gravity was about 1.090 using my hydrometer. I let everything settle and transferred it to a plastic container. I just used a refractometer and it was 1.064. Could the powder that sinks to the bottom skew the gravity reading like that? 1.090 and 1.064 is a big difference in mL needed.

 

[Silver_Is_Money]

Refractometers measure the refractive index of sugar in water. CaCl2 is not sugar.

 

[h22lude]

Refractometers measure the refractive index of sugar in water. CaCl2 is not sugar.

Hmmm I thought all refractometers were the same but I guess brewers ones are different. I know refractometers measure other solutions than just sugar water.

I did just check with my hydrometer and it measured 1.092

 

[portguy]

Hmmm I thought all refractometers were the same but I guess brewers ones are different. I know refractometers measure other solutions than just sugar water.

I did just check with my hydrometer and it measured 1.092

You should read #113 and #116

Now: using Aj's formula and converting your SG 1.064 to Brix i can tell you that the difference is not that big.


Your hydrometer : 111,6 gr/litre

Your Refractometer: 105 gr/litre

There is a 6 gr per litre difference or 11,1% strength vs 10,5% Less than 1% difference between instruments.

BTW: it's late and i do not have my excel file at hand. Maybe AJ will clear that up (including any mistake i made now)

 

[Nordic Brewer]

This hygroscopic (sucks up water) behavior of calcium chloride is kind of a pain in the rear. Over time, it will draw water out of the atmosphere and attach that water to the solids. We brewers end up not knowing how much calcium and chloride we are actually adding to our brewing water.

On the large scale commercial side, some industries use food-grade calcium chloride solutions for their use. Once the calcium chloride is saturated with water, it won't change any further. As AJ mentions above, you can easily use a hydrometer to measure the specific gravity of a calcium chloride solution and quickly figure out what its strength is from charts such as this:

http://http://www.prog-univers.com/IMG/pdf/CalciumChloridHandbook.pdf
(see the first 2 columns in Table 7)

Since calcium chloride is easily dissolved in water, we would be well served by taking our solid calcium chloride and dissolving it in distilled water to preserve its strength at a constant level. The next version of Bru'n Water will include an alternate calculation for liquid calcium chloride use. Just insert the % strength of the solution and it will properly calculate the calcium and chloride additions with each mL of added solution.

Why make things so complicated regarding CaCl2?

If you are going to have a good baseline do the following:

1. Take an arbitrary amount of distilled water.
2. Mix in Calcium Chloride powder.
3. Make sure that you pour in more Calcium Chloride powder than the solution is able to dissolve.
4. You will end up with a solution with a layer of crystals in the bottom.
5. Make sure to seal the container and store it at a place with constant temperature.

The point here is:
The Calcium Chloride powder does not need to be 100% anhydride, actually it does not matter under these circumstances.
The solution above the crystal layer will always be saturated with Ca2++ and Cl-.
The crystal layer containing all variants of CaCl2H20n where n= 0,1,2,4 and 6 will always be in equilibrium with the solution
regardless of temp and vapor pressure.
This is because the crystal layer will act as a buffer to these changes and always make sure that the solution is saturated.

The solution above the crystal layer will have a CaCl2 concentration equal 74.5 g/100 mL (20 °C)

 

[mabrungard]

That approach is similar to that used for using a calcium hydroxide solution. Keep excess solids in the solution and the supernatant will be at its saturation limit. The only problem is that the dissolved content varies with temperature.

 

[ajdelange]

I'd only add one thing to the saturated approach: take an SG reading to check that the solution is really saturated.

 

[Nordic Brewer]

That approach is similar to that used for using a calcium hydroxide solution. Keep excess solids in the solution and the supernatant will be at its saturation limit. The only problem is that the dissolved content varies with temperature.

Thanks for good feedback:
Yes that's true the solubility change with temp, but the solution will remain saturated as long as the crystal layer is intact.
Solubility for CaCl2 is equal 74.5 g/100 mL at 20 °C and 100g/100 mL at 30 °C.
I do not have detailed values between 20C and 30C. Maybe you have Martin?

Due to lack of detailed data between 20C & 30C we can assume the following:
The solubility function for CaCl2 in water is a curved function with respect to temp.
For the sake of simplicity we can assume that the function is linear, to get a estimate that is good enough for home brewing:

Y=kx + A where A=23,5 & k=2,55 between 20C and 30C

20 Celcius: 74,5g = (2,55g/C)*20C + 23,5g
25 Celcius: 87,25g = (2,55g/C)*25C + 23,5g
30 Celsius: 100g = (2,55g/C)*30C + 23,5g

I forgot to mention that as long as the crystal layer is intact, it will also take care of eventually CO2 seeping into the solution.

I hope it is not improper to ask you to read a thread recently I started regarding "pH creep during mashing" at this forum.
I'm very interested to hear your thoughts.

 

[Nordic Brewer]

I'd only add one thing to the saturated approach: take an SG reading to check that the solution is really saturated.

Yes that is a good idea especially if you make the solution in short time before brewing.
In this context time is your friend and it is smart to make the solution in good time.

 

[ajdelange]

I think it a good idea any time. People put lots of reliance on equilibrium conditions and assume that concentrations, activities etc. will be those that examination of thermodynamic equilibrium produce. Thermodynamics gives us a means for computing these quantities at equilibrium but gives us no indication how long it takes to reach equilibrium or indeed it it will ever be reached. In most cases analysis of equilibrium conditions is very helpful and this may well be one of those cases but I do have some concerns. If, for example, one made a saturated solution of calcium chloride at one temperature and allowed it to cool it would be supersaturated at the lower temperature. The argument then is that the crystals would grow as the extra CaCl2 comes out of solution and I don't doubt that this is what happens. But think about making rock candy if you ever did that as a kid. It takes some time for the crystals to grow. I don't have data about CaCl2 in this regard but I'd want to be cautious until I did and would therefore take density measurements until I did. Since it's so easy to do that I don't frankly see much appeal in the CaCl2 case (with Ca(OH)2 we don't really have much choice).

All this is probably mooted by the fact that we are not trying to do certifiable quantitative chemistry here but just get an estimate (±10 - 20%?) of how much CaCl2 we are putting in our mash tuns.

 

[Nordic Brewer]

Yes supersaturation is an aspect regarding crystalization.
I'm not sure if all the reader are familiar with the term supersaturation:
Supersaturation is a state of a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances

An important aspect of supersaturation is "seed crystal" or nucleus (small solid particles)
A liquid crossing its standard saturation point it will crystalize in the precence of a seed cyrstal or nucleus around which a crystal structure can form creating a solid.

When a crystal layer is present in the bottom of a bottle containing supersaturated liquid the surface of the crystal layer will act as crystal seeds hence initiate crystalization of the supersaturated liquid.

Below is an interesting video showing crystalisation of a supersaturated liquid with CaCl2.
There is no crystal layer in the bottom but a little crystal seed is put into the liquid to start the process.
Watch and enjoy

 

[ScrewyBrewer]

Just to make sure I'm doing this right.

I took a 250ml flask, added 20g of CaCl2, and added distilled water to the 200ml mark.

Measured my gravity and it was at 1.070. Enter that into the formula and I get 86.07 g/L.

So if I need 6g of CaCl2 to brew I'd add 6g/86g/L = .069L (69ml), right?

That is exactly what I got too.

 

[portguy]

That is exactly what I got too.
View attachment 578431

That would be 70 mL or 74,45 grams

 

[ScrewyBrewer]

That would be 70 mL or 74,45 grams

Not sure of your math? Is it that I, @LSUGrad0 and others have got different results than you.

 

[portguy]

Not sure of your math? Is it that I, @LSUGrad0 and others have got different results than you.

You are right...it's 74,76 grams.

70mL*0,998203*1,070 = 74,7654047

I find it easier to weigh the solution instead of measuring its volume. That's all.

 

[ScrewyBrewer]

@portgu

You are right...it's 74,76 grams.

70mL*0,998203*1,070 = 74,7654047

I find it easier to weigh the solution instead of measuring its volume. That's all.

@portguy thank you for sharing. It’s true we learn something new every day.

 

[portguy]

@portgu

@portguy thank you for sharing. It’s true we learn something new every day.

No need to thank me! Cheers!

 

[SnowRaven]

Q?

Has the W/W issue been corrected in Bru'n Water v5.3 ?
as I am getting a different result with

W/W = 100*( -684.57 + 175.12*C11 + 509.45*C11^2)/(C11*998.203)
where C11 is the SG

with SG = 1.060 Above yields 6.9441
where BnW yields 6.7

@mabrungard @ajdelange

Just wondering what value I should use in Bru n Water please

 

[SnowRaven]

duplicate post

 

[SnowRaven]

Sharing a
XLS CaCl2 Calculator attached (compressed in a Zip File)
with calcs included in this thread

 

[ajdelange]

Q?

Has the W/W issue been corrected in Bru'n Water v5.3 ?
as I am getting a different result with

W/W = 100*( -684.57 + 175.12*C11 + 509.45*C11^2)/(C11*998.203)
where C11 is the SG

with SG = 1.060 Above yields 6.9441
where BnW yields 6.7

6.9441 is what that formula yields of 1.060 so if he is trying to implement that formula he is doing it wrong. Perhaps he has a different formula

 

[Sudz]

The difference here is about 4%. Is that really a significant factor for our brewing concerns? I for one, find using Bru'n Water's tool much easier than playing with the chemistry in this post. It's good to know the specifics but from a practical perspective, does the added precision bring much to our brewing party?

 

[ScrewyBrewer]

That depends on the brewer. Some like to dot i's and cross t's using a fine point pencil and some don't.

 

[Sudz]

Understand... I'm one of those guys..

However, I do use Bru'n Water and appreciate it's convenience when working with calcium chloride. I just want to insure the differences it may exhibit are not a significant issue for achieving the brew I'm chasing.

Cheers...

 

[Broothru]

The last time I used Bru'n Water (10 days ago) the salt addition tab included a new, separate selection for CaCl and anhydrous CaCl. Might this somehow affect the 'scientific' calculations we're talking about here?

Brooo Brother

 

[Sudz]

The newest version of Bru'n Water has included a method for adding liquid Calcium Chloride among the various dry forms. Possibly this is what you are seeing?