Displacement reactions (1 Viewer)

[Jono10]

Now i am not the best at chemistry, so please try and explain it as best as you can, thanks.

Now say you have a metal, that becomes solution, and the solution becomes the metal

Which one would you say was displaced? Would you say the metal displaced the solution etc

Also by looking at the standard electrode chart, which one can you tell will displace another metal?

 

[minijumbuk]

The metal displaced the metallic ions in the solution, I guess.

You can tell which metal "became solution" (technically called oxidation) by comparing the standard electrode potentials of the two specimen. The higher value of the two when acting as a reductant (losing electrons) is the metal displacing the metal ion solution.

 

[JasonNg1025]

I think the higher metal in the standard potential chart will displace a lower metal. This is because one metal displaces another, it becomes ions in solution like you mentioned, so say you put a piece of sodium in a solution containing magnesium ions. When this happens, the magnesium will become the oxidant:

Mg²⁺_(aq) + 2e^- --> Mg_(s)

And the sodium will become the reductant (getting oxidised):

2 (Na_(s) --> Na⁺ + e^-)

Since the standard electrode potential chart is a standard <i>reduction</i> potential chart, to look at whether or not a metal will be displaced (oxidised, if it becomes ions in solution) you look at which one is more negative. (i.e. which one is further up). A more negative value in the chart will mean a more positive value when oxidising, which means a bigger value when ionising. This is because reduction is the opposite of oxidation.

Summary: A higher metal should displace a lower one in the standard reduction potentials.

 

[Jono10]

When you say the top of the potential chart to you mean the one close to the K or the F

Because its different in different books in chem.

Say if K is the top, so Ca will displace anything below it, making it more reactive and making it the oxidising agent. The metals below Ca will be the reducing agent and will become displaced by Ca.

Is that right?

 

[JasonNg1025]

The top of the reduction table, i.e. close to K. If it was an oxidation table, the bottom would probably have K, and the top have F. Sorry 'bout that.