Warning: Nitric acid is corrosive, wear gloves when handling it.
Nitrogen dioxide and monoxide are toxic gases.
This experiment must be performed outside or in a fume hood.
Greetings fellow nerds.
I needed silver nitrate for some upcoming experiments and to restock my supplies.
While it's not exactly a hard chemical to obtain.
I prefer to make it myself.
Now I already made silver nitrate ten years ago so if you saw the original video then this will just be revisiting old science.
But at least now we can do it in 4k high definition.
First, we start with 75mL of concentrated nitric acid.
You can also use diluted acid but you'll need to readjust the stoichiometry.
You want to have at least 2.5 molar excess of nitric acid.
Now we need a source of silver and i'm going to use a one troy ounce silver coin.
Although technically this is called a silver round.
Silver bullion like coins and bars is the best source of silver for this experiment since it's high purity and the cheapest form to get.
The silver will react very slowly at room temperature, but it does react.
So if you want you can simply leave this in the back of the fume hood for several days and eventually it'll completely dissolve.
Although you may need to add in some water occasionally if you see crystals forming and blocking the silver before it has been completely dissolved.
In anycase, I am not that patient, nor is the memory on my camera that long.
So i'm going to boil the solution to accelerate the reaction.
As you can see, it takes a lot of heating before the reaction rate becomes reasonable.
We need to reach boiling.
And there we go.
So what sort of reaction is happening.
The silver is being oxidized by the nitric acid to form silver nitrate, water, and nitrogen monoxide or dioxide depending on reaction conditions.
The first equation where we consume four nitric acid molecules for every three silver atoms tends to occur in cold and dilute nitric acid solutions.
The second reaction where we consume two nitric acid molecules for every silver atom tends to occur in hot concentrated solutions like we have here.
In reality both reactions are happening to some extent so if you precisely measure the reaction products at the end you'll find it not being perfectly stoichiometric to either one.
So it's always good to run with a molar excess to be sure.
The orange brown gas you're seeing above the reaction mixture is nitrogen dioxide.
Needless to say, nitrogen oxides are quite toxic, so this experiment must be done outside or in a fume hood.
Now if you're really crafty, you can use an airtight apparatus and lead the nitrogen oxides into water or hydrogen peroxide and regenerate the nitric acid.
Personally, nitric acid is easy to obtain for me so I don't bother.
But if you use a lot or it's very valuable to you then it may be something to consider.
As the silver dissolves and produces silver nitrate some of the silver nitrate may precipitate back out.
While this does not harm the reaction, excessive precipitation will block the silver from reacting further.
So adding water occasionally to redissolve the silver nitrate is recommended.
I'm adding in about 25mL of water.
And there we go the silver nitrate is dissolving and the silver is now exposed again so it can react.
Okay, so why would you want silver nitrate.
Silver nitrate has a lot of interesting uses for both amateurs and professionals alike, so it's a useful reagent to have.
On this channel i've used it for simple photography, growing silver crystals, making silver conductive ink and making mirrors.
So making silver nitrate is one of the basic experiments that amateur chemists do when just starting out.
In fact you'll find a lot of videos on youtube doing exactly this.
Okay looks like all our silver is dissolved.
I recommend heating until the solution itself is boiling to ensure that all silver particles are dissolved.
Then turn off the heating and let it cool.
Let the solution evaporate until dry and eventually you should have large crystals of silver nitrate.
This reaction is very robust and the yield should be quantitative at about 49 grams of silver nitrate.
Transfer it to storage container, preferably a brown glass container like this one to protect it from light.
Silver nitrate is slightly photosensitive, so prolonged exposure to strong light will cause it to discolor.
Anyway there you have it, the synthesis of silver nitrate.
I'm going to use it in some upcoming videos like making silver powder.
Thanks for watching.
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