[phd-ph]

Hello fellow chemists! For my home chemistry project, I will need to concentrate sulfuric acid. I don't want to simply boil it down because this wastes a lot of sulfuric acid, so I decided that distillation is the better option.

Since distillation of sulfuric acid is not really a 'safe' thing to do, I wanted to hear your suggestions on the 'best/safest' mode of heating. I will have to reach temperatures of about 350°C, so an oil bath is not an option. I was thinking about the following alternatives:

• round bottom flask heated directly with a Bunsen burner
• round bottom flask heated with Bunsen burner with wire mesh gauze in between
• round bottom flask heated with heating mantle (con: prize)
• round bottom flask heated in a sand bath (con: I have never done this)
• flat bottom flask (con: prize) heated directly with a Bunsen burner
• flat bottom flask (con: prize) heated with Bunsen burner with wire mesh gauze in between
• flat bottom flask (con: prize) heated with heating mantle (con: prize)
• flat bottom flask (con: prize) heated in a sand bath (con: I have never done this)

I appreciate your input

[Borek]

No idea about your local regulations, but often it is easier to just buy concentrated acid than to distill it.

[phd-ph]

I can only buy up to a concentration of 10%. So concentrating it is necessary for me.

Also, it's cheaper for me to electrolytically make my own sulfuric acid either from copper sulfate or magnesium sulfate. I'll have to find out which is cheaper in the long run.

[Corribus]

Most acids for recharging lead-acid batteries are higher concentration than 10%. Available at just about any hardware store and not particularly expensive either. What concentration do you need?

As a side note, I personally wouldn't heat glassware ever with a Bunsen burner. Extremely uneven, a good way to shatter a glass container or have a runaway or uncontrolled reaction. Plus open flames are just, IMO, a good thing to avoid generally in a chemistry lab unless absolutely necessary.

[phd-ph]

I'll need a concentration of at least 90%.

I also thought about car batteries as a source, but for one the concentration is too low for my purpose and I also don't want to deal with lead (oxide) toxicity. In my country, I can't buy sulfuric acid to recharge car batteries (not even a sulfuric acid drain cleaner), so I would have to disassemble a car battery for that.

As a side note, I personally wouldn't heat glassware ever with a Bunsen burner. Extremely uneven, a good way to shatter a glass container or have a runaway or uncontrolled reaction. Plus open flames are just, IMO, a good thing to avoid generally in a chemistry lab unless absolutely necessary.

That's why I was thinking about a wire mesh gauze to distribute the heat more evenly. Do you think a Bunsen burner with a wire mesh gauze and a round bottom flask is save enough? I'm hesitant about a heating mantle because it's expensive. I'll work outside, so there is no concern about open flames in general.