How To: Make sulfuric acid (metabisulfite / oxidizer method)

Make sulfuric acid (metabisulfite / oxidizer method)

Watch this science video tutorial from Nurd Rage on how to make sulfuric acid (metabisulfite / oxidizer method). They show you how to make concentrated sulfuric acid from sodium metabisulfite, hydrochloric acid and an oxidant such as hydrogen peroxide or nitric acid.

Warning: The procedures in this video produce large quantities of toxic gases and deal with highly corrosive acids. All work must be performed in a fume hood with proper safety equipment. And all apparatus must be glass to withstand the acids.

Sodium metabisulfite upon reaction with acid will generate sulfur dioxide. This provides a convenient source of sulfur dioxide that is easier to handle than burning sulfur, but it is acceptable if you want to go that route. You'll just need to build a sophisticated gas capture and scrubbing system so the sulfur vapors and soot don't clog your tubes, poison your air and possibly burn down your workspace.

Sulfur dioxide is converted into sulfuric acid by reacting it with an oxidizer in water. In this case either hydrogen peroxide or nitric acid.

Industrially, sulfur dioxide is reacted with oxygen over a catalyst to make sulfur trioxide. This is cheaper but extremely difficult to do safely for the home chemist so the metabisulfite/oxidizer method is used instead.

You may use potassium metabisulfite instead of sodium metabisulfite. Both are used by home brewers to sterilize winemaking and beermaking mixtures. It's also used for homemade dyeing processes. Therefore it is very easy to obtain the metabisulfites without the need for expensive shipping fees or licenses.

The oxidizers must be present for this reaction to work. You cannot simply use water or you'll just make sulfurous acid which decomposes on heating and is useless for the reactions that sulfuric acid is intended for.

Brought to you by one of WonderHowTo's favorite scientists NurdRage.

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