Relative Reactivities of Metals
Introduction
When a small piece of potassium is dropped into a beaker of water, a violent reaction
occurs. The reaction produces hydrogen gas and a large quantity of heat. The hydrogen
can ignite and burn with explosive rapidity. Similar but much less spectacular reactions
can occur when certain metals are placed in an aqueous solution of a salt.
The reaction of potassium with water is a single-replacement reaction. In a singlereplacement reaction atoms of an element replace the atoms of a second element in a
compound. Single-replacement reactions are also called single-displacement reactions.
A generic example is as follows:
A + BC → AC + B
Whether one metal will displace another metal from a compound can be determined by
the relative reactivities of the two metals. You will determine the relative reactivities of
three metal in this lab.
You will use the two rules to do this:
Rule I:
If a metal, A, reacts with a solution of
metal B’s salt, then A is more reactive than B.

Rule II:
If A doesn’t react with a solution of B’s
salt, then A is less reactive than B.
As an example, consider the following reaction:
Mg(s) + 2AgNO3(aq) -> Mg(NO3)2(aq) + 2Ag(s)
Mg (metal A) reacts with a solution of Ag’s salt (B’s salt), so Mg is more reactive
than Ag.

As another example, consider the following reaction:
Mg(s) + LiNO3(aq) -> no reaction
Mg (metal A) would be less reactive than Li (B’s salt) since it doesn’t react with a
solution of Li salt.
The relative rectivities of the metals may be related to the relative ionization energies
(electronegativities) of the metals. Metals tend to have low ionization energies and
therefore tend to form positive ions relatively easily. Therefore, the most reactive metal
is the least electronegative (ionizes easiest) and the least reactive metal is the most
electronegative (harder to ionize).
Relative Reactivities of Metals
Procedure
**NOTE: Use instructions provide by the instructor – DO NOT USE INSTRUCTIONS
IN CHEMLAB! To remove the instructions on the screen, and free-up more working
area, perform the following operation: click on the OPTIONS tab; then click on LAB
ONLY. The instructions “disappear” and all of the area is now lab space.**
Test tube
1
2
3
4
5
6
Salt Solution
40ml MgSO4
40ml MgSO4
40ml Cu SO4
40ml CuSO4
40ml Zn SO4
40ml Zn SO4
Metal
2.54g Cu
2.62g Zn
0.972g Mg
2.62g Zn
0.972g Mg
2.54g Cu
Step 1: Set up 6 test tubes and label them 1 through 6. Right click on a test tube and add
a thermometer to each test tube.
Step 2: Add the appropriate salt solution to each test tube as shown in the table.
Step 3: Carefully add the appropriate amount of metal to the first test tube. Observe and
note in the observations what happened (an indication that a chemical reaction has
occurred is a temperature change). Note and record any temperature change when the
metal is added. If a reaction occurred, (change in temperature was noted) write the
chemical equation of what happened
Step 4: Repeat step 3 for the second through sixth test tube. Record all data in
Observations.
Relative Reactivities of Metals Name:__________
Observations
Sect:____________
Data
Record your data below. If no reaction occurred (temperature did not change) write “NO REACTION”.
TEST Tube #1:
Observations (including temperature change):
Chemical Equation:
TEST Tube #2:
Observations (including temperature change):
Chemical Equation:
TEST Tube #3:
Observations (including temperature change):
Chemical Equation:
TEST Tube #4:
Observations (including temperature change):
Chemical Equation:
TEST Tube #5:
Observations (including temperature change):
Chemical Equation:
TEST Tube #6:
Observations (including temperature change):
Chemical Equation:
Questions
1. If you were going to do this experiment over again, what would be the fewest number
of tests that you could do (instead of doing all 6 of them) to decide the ranking?
2. On the basis of you observations, what is the ranking of the three metals according to
their activity? Remember when using metal A and the salt of metal B, or metal B and
the salt of metal A, if one reaction works the “opposite” one can’t work!
Highest (least electronegative)
Lowest (most electronegative)
3. Which reaction was the most exothermic?
Discussion