[jonesnaj]

Here we go....

What is the concentration in mg/L of a 5% (weight) solution of DMF (dimethylformamide)?

please correct me if I am wrong, but  for what I understand a 5% solution will have 5 grams of DMF in 100 ml of solution.
If this is right, then this is equivalent to 50gr/Liter ?  and also equivalent to 50,000 mg/L?

[Dan]

It depends whether 5% (weight) means 5% weight/weight or 5% weight/volume - if the latter is true, you are correct.

However, 5% wt usually means 5% weight/weight and 5% weight/volume is normally written 5% w/v or 5% wt/v.

I suspect in this case it is 5 g of DMF in 100 g of solution. Only problem with this is that you would have to know the density of the solution to calculate the molarity accurately.