Metals - Reactivity Series

Objective

To deduce an order of reactivity from a given set of experimental results.

Understanding Reactivity

The reactivity of a metal describes its tendency to lose electrons and form positive ions. More reactive metals readily lose electrons, while less reactive metals are less likely to do so.

Reactivity Series

A reactivity series is an ordered list of metals based on their relative reactivity. Metals higher up in the series are more reactive and will displace metals lower down in the series from their compounds.

Displacement Reactions

A displacement reaction occurs when a more reactive metal displaces a less reactive metal from its salt solution. The general equation for a displacement reaction is:

$M + XnY \rightarrow MX + YN_2$

where M and X are metals and n is a positive integer.

Experimental Results and Deductions

Experimental results often involve observing whether a metal can displace another metal from its salt solution. By comparing these observations, we can deduce the order of reactivity.

Example Experiment

Consider the following experimental results:

• Zinc (Zn) does not react with copper(II) sulfate (CuSO₄).
• Copper (Cu) does not react with silver nitrate (AgNO₃).
• Silver (Ag) reacts with hydrochloric acid (HCl) to produce hydrogen gas (H₂).
• Sodium (Na) reacts vigorously with water (H₂O) to produce hydrogen gas (H₂).

Deducing the Reactivity Series from the Example

From the experimental results, we can deduce the following order of reactivity:

1. Sodium (Na) is the most reactive because it reacts vigorously with water.
2. Silver (Ag) is less reactive than sodium because it only reacts with nitric acid (though not observed in this example).
3. Copper (Cu) is less reactive than silver because it does not react with silver nitrate.
4. Zinc (Zn) is less reactive than copper because it does not react with copper(II) sulfate.

Therefore, the order of reactivity is: Na > Ag > Cu > Zn

Reactivity Series Table

A common reactivity series is shown in the table below:

Metal	Reactivity
Sodium (Na)	Very High
Magnesium (Mg)	High
Zinc (Zn)	Moderate
Iron (Fe)	Moderate
Copper (Cu)	Low
Silver (Ag)	Very Low
Gold (Au)	Extremely Low

Important Notes

• Metals higher in the reactivity series will displace metals lower down in the series from their solutions.
• The reactivity series is a useful tool for predicting the outcome of displacement reactions.
• The reactivity of metals is influenced by factors such as temperature and the concentration of reactants.