How to Make Ammonium Nitrate?

Greetings fellow nerds.

 

In this video we're going to make ammonium nitrate.

 

Ok, let's get started.

 

Now normally ammonium ntirate is made by reacting nitric acid with ammonia, 

but we want to make ammonium nitrate with home chemistry 

so we're going to start with sodium bisulfate.

 

This is available as a pH-lowering chemical for swimming pools.

 

Make sure it says sodium bisulfate somewhere on the container.

 

You can also use sulfuric acid but this substance is usually easier to obtain.

 

Start with 138 grams of sodium bisulfate and add just enough water to completely dissolve it.

 

While that's going, get a mole equivalent of a pure nitrate salt, usually from a fertilizer.

 

The exact quantity you need depends on the nitrate salt you get 

and I’ve listed a few common salts along with the appropriate mass in the video description.

 

I'm using sodium nitrate so I’ve measured out 85 grams.

 

Now add just enough water to completely dissolve it, and then mix the two chemicals.

 

Now you'll need a calibrated pH meter and ammonia.

 

Insert the probe and start tracking the pH, 

it should be very low as the mixture is extremely acidic.

 

Now start adding in the ammonia with stirring and keep going until you go above pH 7.

 

What we're doing is reacting the ammonia with the mixture of sodium bisulfate 

and nitrates to create sodium sulfate and ammonium nitrate.

 

Now because ammonium solutions come in a wide variety of concentrations 

and household ammonia is not always consistent, 

to know how much we need we're using the pH meter to track the pH.

 

When everything is reacted the pH should be neutral or basic.

 

So by using the pH meter we don't have to know what our concentration of ammonia is.

 

Here we are, above pH 7, so the reaction is complete.

 

We now have a mixture of sodium sulfate and ammonium nitrate.

 

At this point, we have to separate the two 

and to do that we're going to take advantage of their differences in solubility.

 

First we need to make a saturated solution, 

boil the mixture until you start to see crystals of sodium sulfate in the bottom.

 

Now take it off heating and put it in the freezer overnight to get it as cold as possible.

 

Here we are the next day and a large amount of sodium sulfate has crystallized out.

 

Filter out the mixture.

 

The filtrate here is ammonium nitrate with some left over sodium sulfate.

 

Just let it dry out. I'm going to pour this into this wide dish to make it go faster.

 

Here we are a couple of days later 

and this is dried ammonium nitrate along with some sodium sulfate contamination.

 

For most purposes this is fine but if you want highly pure stuff, 

we'll need to do one more purification process.

 

Add in 500 milliliters of methanol.

 

Ammonium nitrate dissolves in methanol but sodium sulfate is almost insoluble in it.

 

This provides an excellent means of separation if you happen to have lots of methanol.

 

Now simply filter out the mixture and once again evaporate the filtrate.

 

Mine's a little pink because I used paper towel filters, use coffee filters for cleaner stuff.

 

Anyway, we now have pure homemade ammonium nitrate.