I wanted to verify VaughnH's calculations
, but surprisingly I find that they differ by a factor of 2 (his recipe for a 4dHK solution, according to my calculations, should make an 8dKH solution). To make matters worse, when I test the standard I mixed according to VaughnH's recipe (using 2 different API test kits, BTW), they both return 7dKH (much closer to my calculated number than Tom's). This is scaring the hell out of me because there is no way VaughnH can be wrong!
Please help me find the error in my calculation:
1dKH is defined as 10.71mg of carbonate ion (CO3--) in 1 liter of water.
From the periodic table of elements, I calculated the mass of CO3-- in 1 gram of baking soda (sodium bicarbonate, or NaHCO3) to be:
.714g CO3-- (in 1g sodium bicarbonate, NaHCO3)
Using Tom's recipe, 6 grams of NaHCO3 dissolved in 1 liter of water will yield 4.28g of CO3--:
(6g NaHCO3 / 1L) * (0.714g CO3-- / 1g NaHCO3) = 4.28g CO3--/L
Since there 1dKH = 10.71mg CO3--/L, or 0.0107g CO3--/L, that yields a a dKH value of:
---------------- = 400dKH, not the 200dKH reported by VaughnH
We differ at this point by a factor of 2!!
Continuing with Tom's recipe, he takes 10ml of his standard, which, assuming it's a 200dKH solution, contains 2mg CO3-- and adds that to 500ml of water, yielding a 4dKH sample:
200dKH (200mg CO3--/L or .200mg CO3--/ml) yields 2mg CO3--:
10ml X .200mg CO3--/ml = 2mg CO3--
That's in 500ml of water to yield:
(2mg CO3 / 500ml) * (1000ml / 1L) = 4mg CO3--/L or 4dKH
But when using my obtained 400dKH value for the first solution, the result of the second solution is 8dKH which more closely matches the API test results of the standard I mixed!
If my calculated result had simply missed the mark and the API test kits had shown something close to 4dKH, I'd think I just messed up the math, but since the test results are showing much closer to 8dKH, I went back and checked (then rechecked) the calculations and I can't find a mistake.
I'm hoping someone can find a bug here so that the sky won't start falling because I know VaughnH can't be wrong!!