How to calculate density of (for instance) MgCl2 / water solution

[bartjekwartje]

MgCl2 (Magnesium Chloride)
solubility = 1570gr/l (25gr C)
To mix ~ 2 liter Magnesium stock solution:
Weigh 1500gram MgCl2 and ADD 1 liter RO water.
This solution has now the following concentration 750gr/l (1500/2) => 1gr MgCl2 <=> 1,33ml MgCl2 solution (2000/1500)
- if your consumption is calculated per day at 10 grams MgCl2, then this match with (10/1)*1,33ml= 13,3ml of the MgCl2 solution

I tried figuring out the calculations to get the ml/gram number. I think I came close, but I can't find the density of ro water on the Internet; Using the density of regular pure water as a substitute I got 1,24 ml per gram. What is the density of ro water?

[bartjekwartje]

At first I thought I was using the density of tap water in my calculations and that using the density of ro water would affect the outcome of my calculations such that it would lie closer to the 1,33 ml / gr number. It appears however that the density I used was the density of pure water, which is actually very close to that of tapwater (0.99823 gr/ml at 20 degrees celcius). The density of ro water must lie somewhere between that of pure water and tapwater, and won't make any significant different to the outcome of the calculations. The calculations I made were follows:

A : Density of pure water at 20 degrees : 0.9982 gr/ml
B : Density of MgCl2 at ?? degrees (hexahydrate) : 1.569 gr/ml
C : pure water in mixture: 998,2 gr
D : MgCl2 in mixture : 1500 gr
E : Percentage of RO water in mixture : 100/((1500+998,2)/1500) = 60 % (actually a little bit more than 60 precent, but not significant)
F : Percentage of MgCl2 in mixture : 100 - 60 =  40 % (a little bit less than 40 percent, but not significant)
G : Density of MgCl2 mixed with water : ((E x B) + (F x A)) /100 = 1.341 gr / ml
H : MgCl2 per ml of mixture = 1,341 x F (40 percent) = 0,804 gr / ml
I :  MgCl2 gram per ml = 1/ H = 1,242 ml / gr

Can anyone verify these calculations? Why am I not geting 1,33 ml / gr?

[glennf]

is there any reason why you want to do such a (complex) calculations?

[bartjekwartje]

To get the correct dosis. If my calculations are correct the current suggested values on dsrreefing must be incorrect. In. Case of the mgcl2 mixture the value is off by 7 percent.

[glennf]

To get the correct dosis. If my calculations are correct the current suggested values on dsrreefing must be incorrect. In. Case of the mgcl2 mixture the value is off by 7 percent.

elaborate on that.
tell me exactly what you want to do.
what are you trying to correct ?
what is your measurement, volume and target value.

note:
The solutions were determined by secure measurements with scales and measuring cups.

no need to do any complex calculations.

[bartjekwartje]

The solutions were determined by secure measurements with scales and measuring cups.

Ok thanks, I was wondering about that.

tell me exactly what you want to do.
what are you trying to correct ?
what is your measurement, volume and target value.

The question was not related to a correction.

PS the calculations I made were wrong. It appears it's not possible to calculate the density of the mixture without knowing its volume (which cannot be calculated afaik, only measured).