CHEMISTRY 122: RELATIVE REACTIVITY OF METALS


 
BACKGROUND INFORMATION

The relative reactivity of a group of metals can be established by comparing the reaction of each metal with a given reagent. A metal might react with a specific reagent or no reaction may occur. On the other hand, a given metal might react with a specific reagent at a different rate than some other metal.

In this experiment, the reaction of a group of metals with dilute hydrochloric acid will be used to determine the relative reactivity of the metals. Some metals react with dilute hydrochloric acid as shown in Equation (1).
 


(Equation. 1) M(s) + 2 HCl(aq) ---> MCl2(aq) + H2(g)

At the same time, the rate at which different metals react with dilute hydrochloric acid will vary. Thus, from the laboratory observations as to whether a gas is formed and if so at what rate the gas is evolved, the relative reactivity of the metal can be determined.

A second reaction to be studied in this experiment is the reaction of each of a group of metals with solutions of their corresponding salts. Some metals will react with a solution of a salt of another metal as indicated in Equation (2).

(Equation. 2) M(s) + FeSO4(aq) ---> MSO4(aq) + Fe(s)

In this case, the fact that a metal does or does not rect with a solution of another metallic salt can be used to establish the order of reactivity of a group of metals.

One way to determine if a reaction occurs when a metal is added to a reactant is to note the initial appearance of the metal and the reactant. After a period of time, the final appearance of the metal and the reactant is noted. Any change of the appearance of the metal and the reactant would suggest that a reaction has occurred. In addition, a color change, the formation of a precipitate, or the evolution of a gas would also suggest that a reaction has occurred.


PUT ON
YOUR CHEMICAL SPLASH-PROOF SAFETY GOGGLES!
EXPERIMENTAL PROCEDURE:
A. Initial Appearance of Metals
Examine a sample of magnesium, of zinc, and of copper. Record on the data sheet the observations such as color, texture, and luster.



B. Reaction of Metals with Dilute Hydrochloric Acid
1. Fill three 3 inch test tubes just less than 1/3 full with 2 M HCl.
2. To the acid solution in one test tube, add a SMALL sample of magnesium; to the second test tube add a SMALL sample of zinc; and, to the third test tube add a SMALL sample of copper.
3. Record the observations on the data sheet.
4. Place any unreacted metal and solution in the chemical waste container designated by the lab instructor.



C. Reaction of Metals with Solutions of Salts
1. Fill two 3 inch test tubes just less than 1/3 full with the Mg(NO3)2 solution. Label or place these two in small beakers so as to not confuse them with any other solutions.
2. To one of the test tubes add a SMALL sample of zinc and in the other test tube add a SMALL sample of copper.
3. Record the observations on the data sheet when the metal is initially added to the salt solution and after 10 minutes.
4. Repeat steps 1-3 using Zn(NO3)2 solution, this time adding SMALL samples of magnesium and copper.
5. Repeat steps 1-3 using Cu(NO3)2 solution, this time adding SMALL samples of magnesium and zinc.
6. Place any unreacted metal and solution in the chemical waste container designated by the lab instructor.

CHEMISTRY 122: DATA SHEET FOR MEASUREMENTS
Name __________________________ Hood No. _________________ Date _________________
PUT ON
YOUR CHEMICAL SPLASH-PROOF SAFETY GOGGLES!

A. Initial Appearance of Metals

Metal Observations 

Mg
 

Zn
 

Cu
 
B. Reaction of Metals with 2M Hydrochloric Acid
Metal Initial Observations  Observations after 10 minutes

Mg
   

Zn
   

Cu
   

 

C. Reaction of Metals with Solutions of Salts
Metal with Mg(NO3)2 solution
Initial Observations Observations after 10 minutes

Zn
   

Cu
   

 
Metal with Zn(NO3)2 solution
Initial Observations Observations after 10 minutes

Mg
   

Cu
   

 
Metal with Cu(NO3)2 solution
Initial Observations Observations after 10 minutes

Mg
   

Zn
   



 
1. On the basis of the relative rate of reaction of the three metals with dilute HCl, arrange the metals in decreasing order of reactivity toward dilute HCl.

______ > ______ > ______ > ______
 

2. On the basis of the reaction of the three metals with the salt solutions, arrange the three metals in decreasing order of reactivity.

______ > ______ > ______
 

3. A student was given four metals, A, B, C, and D, and solutions for their corresponding salts, AZ, BZ, CZ, and DZ. The student was asked to determine the relative reactivity of the four metals by reacting them with the solutions.

The results of the laboratory observations of the student are given in Table 1. Arrange the four metals on decreasing order of reactivity.

Table 1

Metal AZ BZ CZ DZ
A NR NR NR NR
B R NR R NR
C R NR NR NR
D R R R NR

R = reaction; NR= no reaction
 

_______ > _______ > _______ > _______