I want to use acetic acid for weed control, but the 5% food grade stuff doesn’t seem to be acidic enough to kill most of the grasses growing in the sidewalk joints.  What would the best way to concentrate it so that I have 1-2 liters of it at 20-30%?

Edited January 29, 20197 yr by Nod2003

Distillation? Check boiling point of water. Check boiling point of compound you want to distill. Check decomposition point of compound. If boiling point is smaller than decomposition point, then you can do distillation, to separate compound from water.

Freezing out the water is also an option- especially in Winter.

Of course, that's not when you need weedkiller, so you need to plan ahead.

Based on google, acetic acid freezes at 16C.  Could I just put the jug of vinegar in the fridge and pour the cold jug through a strainer to get the acetic acid ice which I could then store until needed?

16 minutes ago, Nod2003 said:

Based on google, acetic acid freezes at 16C.  Could I just put the jug of vinegar in the fridge and pour the cold jug through a strainer to get the acetic acid ice which I could then store until needed?

Don't know.

As a non-chemist:

Glacial acetic acid seems to be readily available on the internet.

Diluted as required, it should be much cheaper than using vinegar.

Handle with care.

 

 

 

 

 

4 hours ago, Nod2003 said:

Based on google, acetic acid freezes at 16C.  Could I just put the jug of vinegar in the fridge and pour the cold jug through a strainer to get the acetic acid ice which I could then store until needed?

Oddly, it's the other way round.

There's so much water in vinegar that, when you cool it, the ice crystallizes out first.

Eventually, you get to a mixture where both  freeze out at the same time

There's some discussion of it here

https://chemistry.stackexchange.com/questions/2506/acetic-acid-freezing-distilation