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Old 12-13-2013, 06:34 PM   #11
MachineShopBrewing
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See, that is where you are wrong. The calculation is not 1 lb into 1 gallon is 1.046, it is 1 lb into a solution that results in a final volume of 1 gallon = 1.046. That is the distinction that you are missing in your calculations.



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Old 12-13-2013, 06:44 PM   #12
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With all due respect, I think the calculation does work. You are making the fundamental mistake of confusing volume (Liters) with Weight (Kg). If you mix 1 Kg of a substance into 9 L of water, the only circumstance in which you would get 10 L of solution would be if the density (weight /volume) of that substance was equal to the density of water. In the case of sugar, it is considerably denser than water, so mixing 1 Kg sugar with 9 L water will give the solution a weight of 10 Kg, but a volume less than 10 L.
It is relatively simple to calculate the theoretical volume of the solution.
First, mix 1 Kg sugar in 9 L water. This gives 10 Kg of solution at 10 degrees Plato.
Then use http://www.brewersfriend.com/plato-to-sg-conversion-chart/ to look up the specific gravity of the solution. (You could also use other calculators, but the linked chart provides the formula used to apply the conversion.)
You will find that the S.G. of the solution is 1.040
Using the definition of specific gravity (http://en.wikipedia.org/wiki/Specific_gravity), you can calculate the volume of the solution Volume = Weight / specific gravity * density of water i.e 10 Kg / 1.040 * 1.000 = 9.615 Liters
Note, I have not applied temperature compensation to these figures as you did not specify temperatures.

-a.



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Old 12-13-2013, 07:08 PM   #13
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You are right guys, sorry for this mess. I just didn't pay attention to "... to make 1 galon solution". Sorry again and thank you.

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Old 12-13-2013, 11:48 PM   #14
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the density of the water can change independent of the weight and volume of the sugar addition- this is because the water molecules stay closer together on average when you dissolve something else in them- otherwise gravity would get lower as you added sugar because the water molecules would be pushed farther apart

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Old 12-14-2013, 10:03 PM   #15
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Quote:
Originally Posted by nexy_sm View Post
You are right guys, sorry for this mess. I just didn't pay attention to "... to make 1 galon solution". Sorry again and thank you.
No problem. It is an easy mistake to make. Most people make the same mistake when calculating DME additions for making starters.


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