Saturday, 20 August 2011

Science: How to Copper plate Iron Nails!

This is a super easy to do experiment.  It is safe enough to do with little people like my 6 year old, but covers science topics for older children too as it is all about the displacement of metals.



First of all you'll need:


  • Iron nails
  • 20 - 30 dull copper coins
  • Salt
  • White vinegar (as it needs to be high in acidity to work)
  • 2 glass/clear plastic containers
  • Some kitchen roll
  • A pen
STEP ONE

First of all you need the coins to be dull.  This is because the browny/greeny colour is a coating of copper oxide.  We will be removing this copper oxide in this experiment so keep reading...

STEP TWO

In one of your glass or clear plastic cups place the dull copper coins and a 10 g of salt. 

STEP THREE

Next pour the vinegar in until it covers the coins completely then wait for about 20 minutes.





















STEP FOUR

When you come back to your coins you'll find they look all shiny.  Drain the solution you have made carefully into the other container. 

DO NOT THROW YOUR SOLUTION AWAY

STEP FIVE

Place about 10 - 15 small nails or 5 - 8 bigger nails in the solution.  Leave them there for at least 20 minutes.






STEP SIX

While your waiting label two sheets of kitchen roll.  Label one vinegar/salt solution and on the other label it rinsed. 

STEP SEVEN

Put half the coins straight on to the kitchen roll marked vinegar/salt solution and take the others and carefully rinse them under a tap and allow them to dry on the other piece of kitchen roll marked rinsed. 

What do you think will happen?  Maybe you'd like to write down your predictions (We'll come back to this later though)

STEP EIGHT

Take a look at your nails, what do you see?  They're going a orangey red colour?  That's because the copper is sticking to the iron. 
 


 
Before you take them out of the solution lets look at what has happened to our two sets of coppers...
What has happened to the coppers on the kitchen roll?  The ones in the solution are looking really old, they have brown and green colours.  But the rinsed ones are still bright and shiny! 
 
Why?

Well the copper that's in the solution reacts quicker with the air around turning the copper into copper oxide much quicker.  The rinsed ones are different though, there is less copper on the outer layer.  They will go back to being dull but it will take much, much longer!
So back to the nails...
 
Take them out and have a look at what has happened - if you want them to stay shiny copper nails for a while.  Don't forget to rinse them!
 
Have fun experimenting!

If you want to learn more about the science behind this experiment read on...

 
The reactivity series is metal is an arrangement of the metals in order of their reactivity starting with the most reactive metal at the top and ending with the least reactive metal at the bottom.
 
The reactivity of a metal is determined by its ability to form a positive ion. For example, potassium is extremely reactive because it has only one valence electron, so it is very easy to lose it forming a positive ion.
 
On the other hand, copper is a weakly reactive metal because it has more valence electrons so it is harder for it to become a positive ion.
 
So What exactly is happening?
 
The copper oxide, the brown tarnish that covers our copper pennies is removed from the old pennies because of the reaction between salt and vinegar -
 
When salt and vinegar is mixed, sodium acetate is formed.
 
Chemical formula for Sodium Acetate: CH3COONa
 
Sodium Acetate is used in for things like seasoning food or as a photoresist in using aniline dyes.
 
Whichever metal is most active the sulphate will be most attracted to. 
 
In this copper plating nails experiment you had the Sodium acetate remove the copper oxide leaving particles of copper floating around in the solution, as soon as you add the iron nails you will notice fizzing, you will see bubbles again the nails.  After 5 or so minutes you will see the nails change colour this is because Iron (Fe) is a more reactive metal as you can see on the chart therefor the copper ions in the solution are more strongly attracted to the iron and this is why the nails get coated in copper.
 
The reaction in formula looks like this...
 
iron + copper acetate copper + iron acetate
 
Fe(s) + Cu(II) CH3COONa (aq)  Cu(s) + Fe CH3COONa (aq) 
 
s = solid
 
aq = dissolved in water
 

2 comments:

  1. Great post, now on the list of things to try, must do more science experiments with the kids.
    It's also possible to do this using electricity (electroplating) you can also copper plate things like acorns and such like, but requires some extra equipment, which may be pricey (I intend to build my own electroplating machine)

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  2. I saw the electro placting. I think the make your own electroplating machine seems like an extra science lesson in itself!

    I'm curious now and will look into it! :)

    Glad you like the post x

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