Make Sulfuric acid (metabisulfite/oxidizer method)

Uploaded by NurdRage on 28.06.2009

Greetings fellow nerds.
Sulfuric acid is an extremely useful acid
and there are many methods of making it.
We'll be be showing one method here.
First we need to make a sulfur dioxide generator.
In this case get a 3 necked flask
and fill it with 50grams of sodium metabisulfite.
Then add in a stir bar and 50ml of water.
On one side, hook up a gas adapter and outlet tube.
I'm using a stoppered distillation adapter because I couldn't find my actual gas adapter.
Obviously when you do yours use a proper gas adapter.
Now get a 25mL graduated cylinder and a beaker that will fit it.
Our gas outlet tube has a gas dispersion tube end
but you can use a straight tube if needed.
Ok, lead the tube into the cylinder.
Now connect a pressure equalized dripping funnel to the flask.
Stopper off the extra neck of the flask.
Now fill the funnel with 50mL of concentrated 12 molar hydrochloric acid.
Be sure to stopper off the top of the funnel so the gases don't leak out.
Now fill your graduated cylinder with 25mL of 30% hydrogen peroxide
and fill the beaker with ice to form an ice bath around the peroxide.
Ok let's go in for a close up.
And now carefully open the dripping funnel
and very carefully let the hydrochloric acid in drop by drop.
If you mix them too fast the sudden burst of gas will splatter your peroxide.
Now just let the reaction go until the gas generator stops bubbling.
Now I'm using hydrogen peroxide as the oxidizer
because it's cheap and readily available.
But it doesn't give a high yield or a decent concentration of acid.
A better oxidizer is the concentrated nitric acid
made from the first two methods we showed in our nitric acid video.
Reaction with sulfur dioxide will produce copious amounts of nitrogen dioxide.
The advantage of this is that it indicates when the reaction is complete.
When it goes completely clear
all the nitric acid has been converted into sulfuric acid.
You can then swap out more nitric acid to continue the reaction.
Hydrogen peroxide does not give you this indication.
Alright, in either method, take out the cylinder from the ice bath
and let it warm back up to room temperature.
As it does so some of the excess sulfur dioxide will bubble out.
Boil the acid to both concentrate it and remove the remaining sulfur dioxide.
As the concentration rises due to loss of water
the acid itself will eventually start to vaporize,
producing a very distinctive fuming as seen here.
These dense fumes start as the acid passes 70% concentration.
You'll need to heat the acid past 300 Celsius
in order to reach better than 95% concentration.
And here is the clean acid.
To test it, simply mix it with an equal portion of sugar.
The dehydration of the sugar will cause it to blacken and expand.
Like I said in the beginning there are many ways to make sulfuric acid
and we might show them in upcoming videos.
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