Converting from %Weight to g/L


Thread Starter


Dear Friends,

In our facility we are using an analyzer that measures %Weight concentration of two solvents (%Wt of X in water solution, and %Wt of Y in the same solution) simultaniously and the temperature.

An example existing output:
- NaOH in solution: %8 Wt
- NaCl in solution: %12 Wt
- T = 20 Celcius

An example desired output:
- NaOH in solution: 15 g/l
- NaCl in solution: 26 g/l

In order to make the measurements useful I need to output them in the units of g/L. Can someone explain how can I go from %Weight to g/L? I couldn't come up with a formula to solve it. I would appreciate your help.
one liter H2O = 999g / 20 DegC

8% Wt-> 80 grams per liter of water
12% Wt -> 120 grams per liter of water

a rough estimate for the mixture

Wt(NaOH) =100*80(g/L)*density NaOH(est. 2.130)=170.4 g

Wt(NaCl)= 100*120(g/L)*density NaCl(est. 2.163)=259.6 g

Wt%(NaOH) = 17 % of 1000g Mixture
Wt%(NaCl) = 26 % of 1000g Mixture

the actual data is usually tabulated
Thanks a lot for the detailed answer. I have a question:

1) You wrote: ">8% Wt-> 80 grams per liter of water". In my understanding, %8Wt=Weight of NaOH/(Weight of H20 +Weight of NaOH+Weight of NaCl). But in your formulation, %Wt(NaOH)=Weight of NaOH/Weight of H20, what I believe is incorrect. I may be wrong, but according to my internet research my formula should be the correct one. Waiting for your comments.
I started with one liter of pure H2O then added the specified weight of NaOH.

Since you are starting with Wt/L and desire Wt/Wt % you must account the nominal density of the added components (in this case crude at best since the compounds are actually dissolved).