Can we walk through one?
CaCl2 for example.
Atomic Weight of Ca is 40.078
Atomic Weight of Cl is 35.453
Ca (40.078) + {Cl (35.453) (2)}
total weight: 110.983 grams = 1 mole.
1 gram = .0009 moles
1 gram of CaCl = .0009moles and therefore 1 mg would equal .0000009 moles.
(
http://environmentalchemistry.com/yogi/reference/molar.html#Calculator)
Cl= 63.89%
Ca= 36.11%
Therefore, 1 mg of CaCl2 added to 1 liter of water would be 0.36 mg Ca and
0.64 mg Cl...
and
.36mg/L = .36 ppm right DS?.... so to raise Ca by 100 ppm,
you would have to add 277 mg/L (100 divided by .36), or .277 grams /liter (move decimal to convert mg to g), rounded up to .28 grams /liter.
it should be .28 grams per liter... based on above calculations, right?
.28 grams per
LITER (not gallon) to raise Ca by 100ppm. This would also add roughly twice as much Cl (200 ppm)
its actually about 1 gram per gallon to raise ppm by about 100 (98% cacl2 not pure). Thats pretty simple.
Does this look right to you guys?
0.23127 oz =/= 28.35 g. and a us gal is still 3.7854 L (small typo).
100 ppm Ca
98% pure > 100/.98 = 102 ppm or mg/L
mass of CaCl2 > 102 mg / 0.361 = 282.7 mg or 0.283 g/L
he should have said 28.3 g (roughly an oz) per 100 L. you get the gold star, and fatman gets to wear a helmet :)
fatman diy is still a great thread to learn this stuff. the u of m link with the ppm tutorial is broken. it's been covered pretty well, but here's another.
solute is the stuff being dissolved - in our case salts.
solvent is the thing doing the dissolving - water aka aqueous.
solution is water that has solute dissolved in it.
note that units are multiplied and divided, just like numbers. i.e. L ÷ L = 1
mg/L x L = mg
mg/g x g = mg
this is a quick check to make sure you're following the correct order of operations. if you do a unit check, and you get mg squared, you've done something wrong.
1 L of an aqueous potassium oxide solution contains 0.5 g K2O.
Calculate the concentration of K2O in parts per million (ppm).
ppm = mass solute (mg) ÷ volume solution (L)
what we know:
mass K2O = 0.5 g x 1000 mg/g = 500 mg
volume solution = 1 L
ppm = ???
solve for ppm
concentration of K2O = 500 mg ÷ 1 L = 500 mg/L = 500 ppm of K2O
if we want to know the mass proportion of K in K2O, we refer to wiki and/or a periodic table of elements.
molar mass for
K = 39.0983 g/mol
O = 15.9994 g/mol
a chemical equation always has the number of atoms represented by a digit in the subscript. no subscript implicitly means one atom. hence K2O has two potassium, and one oxygen.
K x 2 + O
= 39.0983 x 2 + 15.9994
= 94.196 g/mol of K2O
mass percent of K
mass of K ÷ mass of K2O
39.0983 ÷ 94.196
= 0.8301
K makes up 83% of K2O
concentration of K2O in solution = 500 ppm of K2O
concentration of K
500 ppm K2O x 83% K/K2O = 415.1 ppm K
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we can rearrange the equation to solve for different variables given different known quantities:
ppm = mass solute (mg) ÷ volume solution (L)
volume solution (L) = mass solute (mg) ÷ ppm
mass solute (mg) = ppm x volume solution (L)
e.g. what mass of K2O (in g) do we need if we have 1 L aqueous solution of of 100 ppm K?
we know:
ppm of element = 100 ppm
mass proportion of K to K2O = 0.83
volume of solution = 1L
solve for mass of K2O
100 ppm K = 100 mg/L K
mass solute (mg) = ppm x volume solution (L)
mass K = 100 mg/L x 1 L = 100 mg
mass of K2O
100 mg K ÷ 0.83 K/K2O = 120.5 mg K2O
120.5 mg x 1 g ÷ 1000 mg = 0.12 g K2O
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