Displacement Reactions and Electrochemical Cells

Displacement Reactions in Chemistry

In a displacement reaction, a more reactive element takes the place of a less reactive element in a compound.
These reactions involve the movement or “displacement” of ions.
The reactivity series helps us to predict the outcomes of displacement reactions. In descending order, it includes elements like potassium, sodium, calcium, magnesium, zinc, iron, lead, hydrogen, copper, silver, gold.
For example, if copper sulphate solution is added to iron filings, the iron will displace the copper because iron is more reactive. It forms iron sulphate, and copper is left as the displaced element.
Remember that in these reactions, the more reactive metal loses electrons (oxidation) and the less reactive metal gains electrons (reduction).

Electrochemical Cells in Chemistry

An electrochemical cell involves a chemical reaction that produces an electric current, or an electric current that drives a chemical reaction.
It consists of two electrodes (often different types of metal), each placed in an electrolyte. The two solutions are often connected via a salt bridge.
One metal can act as the anode, which is the electrode where oxidation occurs. This means it loses electrons and forms ions. The process might, for example, involve zinc atoms losing electrons to become zinc ions.
The other metal can act as the cathode, which is the electrode where reduction occurs. Here, ions gain electrons to become atoms, like copper ions gaining electrons to form copper atoms.
The electrons lost by the anode move through the connecting wire to the cathode, generating an electric current.
The movement of ions in the electrolytes and the salt bridge help keep the charge balanced in the cell.
Voltmeters can be used to measure the potential difference or voltage produced by the cell, which is affected by the type of electrodes and electrolytes used, among other factors.
These principles underpin the workings of all sorts of batteries and fuel cells that power our daily lives.