g/L to weight%

[Anon]

Hi all,
Can you please help me convert from g/L to weight %? (Chemistry)
I have a sample from sugar refinery and I know the concentration of sugar in the sample (378g/L). The sample also has salts, organic acids etc. How do I convert this to weight %? Should I use density? In which case should it be density of the solution? I'm not sure if it should be density of water because the solution looks brown and viscous. Thanks in advance!

[JohnS]

You need the density of the solution. This sounds like a pretty concentrated solution, just from the sugar, so it will be quire different from water. The problem with percentages is that you have keep specifying the basis (weight/weight) or it is meaningless. You might want to consider stating a mass proportion as grams per kilogram, g/kg. Note that "1 g/kg" is "0.1 % (w/w)" but is actually shorter to write out. Just divide your g/L figure by density expressed as kg/L (should be somewhat greater than 1 in this case)

For dilute solutions, less than 0.5%, it is usually safe to assume the density is very close to that of water. But that is not the case here.

[Anon]

Thank you very much for your help JohnS!

[Amit bajpayee]

You need the density of the solution. This sounds like a pretty concentrated solution, just from the sugar, so it will be quire different from water. The problem with percentages is that you have keep specifying the basis (weight/weight) or it is meaningless. You might want to consider stating a mass proportion as grams per kilogram, g/kg. Note that "1 g/kg" is "0.1 % (w/w)" but is actually shorter to write out. Just divide your g/L figure by density expressed as kg/L (should be somewhat greater than 1 in this case)

For dilute solutions, less than 0.5%, it is usually safe to assume the density is very close to that of water. But that is not the case here.

Hi JohnS,
Thank you for the information, this really going to help many students.

[MdMehediSH]

hi, how are you?

[foysalalam750]

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.

[JohnS]

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.

Your solution is 80 g/kg NaOH and 120 g/kg NaCl. You would have to measure the density of your solution and multiply by it. I am strictly guessing (you need to measure) but lets say hypothetically it is 1.1 kg/L. Multiply by the density and you get 88 g/L and 132 g/L (because a liter has mass greater than 1 kg)

[beetecaste]

Thank you very much