This activity tests a student's ability to understand the reactions between Metals and Acids.
First off, when an acid reacts with a metal, the acid will react with the metal to produce the metal salt of that acid; at the same time, it will produce hydrogen gas.
What does that look like? The general path of these metal/acid reactions is:
Acid + Metal Salt + Hydrogen
(NB: note that the word 'salt' here refers to a metal salt, i.e. a compound of the metal which has been formed through reaction with an acid, e.g. zinc chloride, potassium nitrate and iron sulfate are all metal salts).
Here are two examples of reactions of different metals with dilute acids:
Magnesium + Hydrochloric Acid → Magnesium Chloride + Hydrogen
So where did the 'sulfate' or 'chloride' come from? It might help to use compound names for these acids - after all, they are all compounds of hydrogen in solution. Try this:
Now look back at those two word equations above - can you see where the zinc sulfate and the magnesium chloride have come from? Let's check out one more:
Copper + Nitric Acid → Copper Nitrate + Hydrogen could be re-written as:
Copper + Hydrogen nitrate → Copper nitrate + Hydrogen
In all of the above reactions, the metal has taken the place of the hydrogen in the acid and formed a metal salt. It's a type of displacement reaction.