[opening music]
Hi everyone, welcome back to Cody's Lab.
So here is a glass of water,
and here is a piece of sodium metal.
Now you probably all know what happens
when sodium metal reacts with water,
but just as a refresher, here we go:
You see, there is quite a vigorous reaction taking place here.
What's happening is that the sodium metal is so reactive,
it's able to replace hydrogen in the water molecule,
forming sodium hydroxide and releasing the hydrogen gas.
It also releases lots of heat.
Now that the sodium is used up,
I now have a solution of sodium hydroxide in water.
Now I have over here another beaker which contains silver nitrate.
In fact, this is a concentrated solution which
contains as much silver nitrate as I could get to dissolve at this temperature.
Now if we pour a little bit of the silver nitrate into the sodium hydroxide solution,
we should see a dark black or brown precipitant.
So there we go.
Now what this is, is silver oxide being produced.
Now, the silver is very unreactive, it wants to be as close to its elemental state as possible,
and silver nitrate is not an elemental state.
But sodium is happy to have this nitrate ion,
so sodium goes on and makes a sodium nitrate,
and the silver reacts and forms silver hydroxide.
Now, the silver hydroxide is also reacted with water,
so it immediately forms silver oxide.
I'll put all the reactions somewhere on screen.
So, now we have a solution with silver oxide.
But, this begs the question,
what happens if I put the sodium into the silver nitrate directly?
So, let's try this and find out.
Here's a nice shiny piece of sodium metal,
there's my silver nitrate solution,
let's drop it in and see what happens.
Okay...
nothing seems to happen at first...
I do see a little bit of a black silver oxide forming...
so I imagine that's because the sodium is reacting with water forming
so- sodium hydroxide-
ooh!
That was unexpected!
That ignited!
That was a very vigorous reaction, actually!
That was interesting!
Did not expect that.
So let's see what we got.
Hold this up,
look inside of there,
there's some reactions going, so there was a little bit of sodium metal still...
there's definitely some hard white material in there.
Let me get a piece of that out and have a look at it.
So I just pulled some of the material out of the flask,
so this dark, brownish black stuff, that's pretty obviously silver oxide,
but this hard, white material, right there?
which was what was coating the sodium metal,
was a bit more of a mystery to me.
But after looking at it a little bit closer I've determined that it is actually silver nitrate.
So what I think's happening here, is the sodium is pulling the water out of the silver nitrate solution,
leaving behind silver nitrate salt,
which is hot enough that it melts.
And when it solidifies it forms a nice hard white material.
But while it's molten, silver nitrate will react with sodium metal,
similar to how potassium nitrate will react with sugar.
So we're actually burning the sodium metal.
That reaction should form silver metal,
sodium oxide (which then will react with water),
and nitrogen gas.
So to see if any silver metal is actually formed,
I've now poured off all the silver nitrate solution, leaving the black sludge at the bottom,
and now I'm going to add some ammonia.
Now, this is ammonium hydroxide,
and that should be able to dissolve the silver oxide, but it won't dissolve silver metal.
So if we're left with silver metal, it should be rather obvious.
So I have now obtained a mostly clear solution,
let's bring this over to the light so we can see it better,
so there's definitely some material down at the bottom still,
in fact,
look at this,
I'd say there's actually some little beads of silver metal!
So we did form silver.
How bout' that!
So let's pull one of those out there so you can see it better.
So there it is, a little bead of silver metal.
It's about a... millimetre wide or so?
Yup, we did form silver!
So that was a fun little experiment,
hope y'all enjoyed,
I'll see you next time.
[ending music]