How do acids in Coca-Cola clean a coin?

Coca Cola contains a very important chemical substance called Phosphorous Acid.

The chemical formula is H3PO4.

This means that this chemical is formed out of 3 atoms of Hydrogen (H3), 1 atom Phosphorous (P) and 4 atoms of Oxygen (O4). A collection of atoms you call a molecule, in this case a Phosphorous Acid molecule.

When you add water to this acid, Coke is a lot of water, the molecule will break apart, into 4 pieces.

H+ H+ H+ (3H+) and PO43-. Those pluses and minusesare the electrical charges that hold together the molecule. We have 3 pluses and 3 minuses. when you add a plus and a minus you get zero, this means balance, order, rest in chemistry, but water weakens the electrical forces by about 80 times. So the molecule falls apart, except for the PO43- part, that's even too strong for water.

Phosphorous is very important for humans, it makes it you can think!

Now metals (as in coins) can react with strong acids like our H3PO4 or to be more accurate, with the H+ atom. (an atom with a + or a -, we must call an ion) the H+ ion will "get" a minus particle, called an Electron, from the metal, which then becomes a Metal+ ion.

This Metal+ ion will not stick to the coin any more, and comes of with the dirt from the coin on it.

There is also a second process going on giving the Phosphorous Acid access to the metal of the coin.

Most of the time the stuff that makes the coins dirty are fat (fatty acids or lipids) and oxides (rust).

Well Phosphorous Acid can deal with that too. It will break down the fat and reduce the oxides.

The third process

The bubbels in the Coke (Carbondioxide) will bubble the dirt more lose.

The H+ ions getting the Electrons will eventually cling (they are stronger than water too) together and form Hydrogen gas(H2) , this gas will also bubble the dirty away.