So where were we, ah yes, we’ve just taken the cake out of the oven and it looks “interesting”. A slab of brown cake like stuff, looking good. We cut into it and the whole thing falls apart, and another aspect to cookery becomes apparent: you need to measure your ingredients. Just pouring stuff into the bowl doesn’t work.
So, how much do we use? For that we have to delve a little into chemistry looking at how much “stuff” weighs so we can weight it out.
The important factor is that we add calcium and carbonate in the same relative quantity that they are consumed. Biologically the consumption is
which means take one atom of Calcium and two molecules of Carbonate which combine to form one molecule of CalciumCarbonate, one molecule of
carbon dioxide and one molecule of water. From this we can tell several things:
- That it is the Calcium (Ca) and Bicarbonate (HCO3)
that are the inputs
- That two units of Bicarbonate are used for each unit of Calcium
- That carbon dioxide and water are by-products of calcification
So we need to ensure that we add the ingredients in the same
proportion, that is two units of Bicarbonate for each unit of Calcium, and that
we balance out the resulting NaCl with NaCl-Free salts.
In chemistry most measurements of the ‘amount’ of a molecule
Is done in mol. Each mol of a substance contains the same number of elementary
entities (atoms, molecules, etc), and normally it is the gram-mole which is
used. A gram-mole is the quantity of a substance whose mass in grams is equal
to its formula weight. This makes it quite easy to weight out substances so
that they are in the relative quantities we need.
The important bit is working out the formula weight and for
that we need to understand a little more about atoms. Each atom has a
particular mass and these are well known quantities and appear on a periodic
table of elements. The important elements to us for this purpose are:
and the way to determine the molar mass is to add up all of
the bits to get the total atomic weight for one entity and then that amount in
grams is one mole. Showing this makes it much easier:
Determine the atomic weight of CaCl2
0 by adding the atomic weights of the parts:
First determine the atomic weight of CaCl2
40.078 + 2x35.453 = 110.984
Then determine the atomic weight of H2
2x1.00794 + 15.9994 = 18.01528
Then add them together remembering we have two molecules of water
110.984 + 2x18.01528 = 147.01
Determine the atomic weight of NaHCO3
2.9898 + 1.00794 + 12.0107 + 3x15.9994 = 84.00664
So from this we now know that one mole of CaCl2
weighs 147.01 grams and one mole of NaHCO3
weighs 84.00664 grams. Thus
as we need twice as much of one to the other it is simply a case of weighing
out the proportionate amount, which is where Balling gets his often used
- 147g of CaCl2-2H2O
- 168g of NaHCO3
and he dilutes each of those to 2L of water, which now
means that the same quantity of water from each contains proportionally correct amounts of the two ingredients.
That dilution is done to a total volume of 2L, not 2L of water plus the ingredients, so the best way
is to measure out 1.5L of water, add the chemicals and then top up to 2L by adding more water.
In those two mixes we now are adding those bits we want, and
those bits we don’t which as we noted before is the Na from the NaHCO3
and the Cl2
from the CaCl2
. Fortunately we are adding
twice as much NaHCO3
as we are CaCl2
so for each unit of
addition we have two units of NaCl resulting. So for each 2L added we are
adding two moles of NaCl.
The atomic mass of NaCl is 58.443 which means we are adding
116.89 grams of NaCl for each 2L mix we add. As NaCl represents 70% of the
ingredients of marine salts we now have to add the remaining 30% to get to a
full marine salt mix. As 70% weighs 116.89 grams it means 100% weighs 167g,
meaning that the 30% weighs 50 grams, once again the figure that Balling uses
as the third container, a mix of 50g of NaCl-free salts to 2L water.
So we have ended up with three mixes of which we add in the
same quantities to ensure a balanced addition that adds Calcium, Carbonate and
balanced marine water.