Displacement reactions between metals and their salts

What are we doing? https://www.youtube.com/watch?v=4Hf7PH9ZYgA Some metals are more reactive than others. In this experiment, a strip of metal is added to a solution of a compound of another metal. A more reactive metal displaces (pushes out) a less reactive metal from its compound. In carrying out the experiment, you will investigate reactions of metals and arrive at a reactivity series of the four metals you use.

Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and non-metals take part in displacement reactions.  Displacement reactions involve a metal and a compound of a different metal. E.g - Reaction of iron nails with copper sulphate solution. Layer of copper displaced onto iron indicating the iron is more reactive.

Reminder You are looking for cases where one metal displaces another. Some of the solutions are slightly acidic so that bubbles of hydrogen are sometimes seen. NOTE: This does not count as displacement of one metal by another.

Results

Results No reaction = no observed change, in some cases where theoretically there should be a reaction, you might not see any change (see Al note below). Aluminium, again gives problems with the observations because of the oxide layer inhibiting the reaction with the salt solution of a less reactive metal. The displaced copper can display a variety of colours depending on how the precipitate-coating forms, and how much of it - I'm afraid that's the way it is! In some cases the metal crystals formed by the displacement reaction are very small and scatter the light so that they can look quite dark - almost black, rather than a silver-shiny precipitate

Conclusions and Comments Any colour change indicates a displacement reaction has occurred, AND the rule is that a more reactive metal will displace a less reactive metal from its salt solution (irrespective of which salt) Of the series of metals tested magnesium appears to be the most reactive because it displaces all the other metals being investigated here. Copper appears to be the least reactive in this limited series because it does not displace any of the other metals. Therefore by considering what will displace what from the results table, you can quite legitimately deduce that in terms of reactivity order magnesium > aluminium > zinc > iron > lead > copper BUT the observations for aluminium and lead may not show up clearly. What you can definitely deduce in a more restricted experiment is the reactivity series order magnesium > zinc > iron > copper

Reactivity Series – Arranges metals in order of their reactivity

Key Points The more reactive a metal is: the more likely it is to form a compound the more stable its compound the more difficult it is to extract from its compounds Copper, silver and gold appear as elements in the earth due to their unreactivity with their environment. They are easy to extract. Reactive metals are more difficult to extract. They are often found as compounds or ores. A method of extraction known as Electrolysis is used to remove the element from the remaining compound