EXPLORING REACTIVITY LABORATORY 6 THE CHEMISTRY OF METALS

GEORGIA MILITARY COLLEGE

NATURAL SCIENCE DEPARTMENT

ONLINE CAMPUS

LABORATORY 6 – THE CHEMISTRY OF METALS: EXPLORING REACTIVITY

NAME

STUDENT NUMBER

CLASS

PROFESSOR’S TITLE AND NAME

Introduction

This laboratory explores the concept of reactivity in metals. A metal’s reactivity is a measure of the ease with which it reacts with other substances (Hein et al. 2023). Some metals such as sodium are highly reactive, while others such as platinum and gold are inert (Hein et al. 2023). Generally, how reactive a metal is depends on the ease with which it loses electrons in its outer shell to form cations (Hein et al. 2023). Metals that lose electrons easily are more reactive than those that do not easily lose the electrons in their outer shell. The reactivity series is a list that arranges metals by reactivity, with the least reactive at the bottom and the most reactive at the top.

It is important to study metal reactivity because such knowledge helps in predicting how different metals would behave in a chemical reaction, and hence, what metal to choose for a certain function (Hein et al. 2023). For instance, very reactive metals such as sodium and potassium react vigorously with oxygen and water and could be used in developing explosives. At the same time, inert metals such as gold and silver that do not easily corrode are good for making coins and jewelry.

A reactive metal has the capacity to displace another that is less reactive from its salt aqueous salt solution (Hein et al. 2023). Taking the example of zinc immersed in copper (II) sulfate, zinc displaces the copper in the aqueous copper (II) sulfate solution, leading to the formation of zinc sulfate and copper as shown in figure 1 (Hein et al., 2023):

Zn (s) + CuSo4 (aq) = ZnSo4 (aq) + Cu (s). ……………………………………Figure 1.

Zn, the free metal, is more reactive than Copper (Cu). It loses electrons and dissolves into the salt solution. At the same time, the less reactive copper (II) ions accept the electrons donated by zinc to form the free metal Cu.

The net ionic reaction between the elements can be presented as:

Zn(s) + Cu2+ (aq) => Zn2+(aq) + Cu(s).....................................................figure 2

This could further be simplified to a general reaction of this form:

A(s) + B+ (aq) => A+(aq) + B(s)……………………………………figure 3

Figure 3: A(s), a free metal, donates an electron and dissolves into the cation A+(aq), which forms the salt solution, while cation B+ (aq) accepts an electron and converts to the free metal B(s).

However, free metal A has to be more reactive than ion B+ for the reaction to occur. Relative reactivity is the comparison of different metals by reactivity using a standard media, such as their reaction when placed in water or acid. The factors to look for in relative reactivity include:

i) Change in temperature

ii) Formation of a solid precipitate

iii) Evolution of gases , which is shown through the presence of bubbles

iv) Dramatic change in color

This lab involves performing a series of redox reactions to analyze the relative reactivity of four metals: lead, zinc, magnesium, and copper. Its objective is to enhance understanding of concept of relative reactivity of metals. The general hypothesis is that the alkaline earth metals (magnesium and zinc) are more reactive than transitional metals (lead and copper), because they lose electrons more easily.

Materials and Methods

Preparing the Lab

i) Click on the link labeled ‘Virtual Lab’ on the course home page to load the lab environment.

ii) Load the assignment via the ‘File’ option and choose the ‘Redox’ category.

iii) Select the assignment titled ‘Redox Reaction Series.’ This sets the stage for the first experiment.

Performing the Lab

iv) In the ‘Stockroom’ select the ‘Glassware’ tab and choose 5mL pipette and 250mL Erlenmeyer flask.

v) Choose 0.1M magnesium nitrate solution from the ‘Solutions’ tab and move the flask containing the solution to the workbench.

vi) Choose the container with ‘Cu’ metal from the ‘Solids’ tab and move it to the workbench.

vii) Using the pipette, transfer 5mL of 0.1M magnesium nitrate to the 250mL Erlenmeyer flask and record the solution’s initial temperature.

viii) Transfer 1g of Cu metal to the flack containing the magnesium nitrate solution and record the temperature as well as any other changes that occur.

ix) Clear the workbench and start again, with another solution/metal combination as shown in table 1.1.

Data Collection

x) Record the observations from each solution/metal combination in table 1.1

Data Analysis

xi) Carefully analyze the data collected in table 1.1

xii) List the four metals by order of relative reactivity, starting with the least to the most reactive.

xiii) Justify your selection in (xii) above:

Data and Discussion

Data

Data table 1.1

Solution

Temperature

Metal

Signs of Reaction

Net Ionic Equation

Mg+2

Cu

None

Cu(s) + Mg2+ (aq) => Mg2+(aq) + Cu(s)

Zn+2

Cu

None

Cu(s) + Zn2+ (aq) => Zn2+(aq) + Cu(s)

Pb+2

Cu

None

Cu(s) + Pb2+ (aq) => Pb2+(aq) + Cu(s)

Cu+2

31.00 going down to 26.74

Mg

Temperature change, color change from blue to colorless, formation of brown solid (copper)

Mg(s) + Cu2+ (aq) => Mg2+(aq) + Cu(s)

Zn+2

30 going down to 25.00

Mg

Temperature change

Mg(s) + Zn2+ (aq) => Mg2+(aq) + Zn(s)

Pb+2

35.00 going down to 25

Mg

Temperature change

Mg(s) + Pb2+ (aq) => Mg2+(aq) + Pb(s)

Cu+2

27.00 going down to 25.3

Zn

Temperature change, color change from blue to colorless, brown solid forms (copper)

Zn(s) + Cu2+ (aq) => Zn2+(aq) + Cu(s)

Mg+2

Zn

None

Zn(s) + Mg2+ (aq) => Mg2+(aq) + Zn(s)

Pb+2

27.00 going down to 25.00

Zn

Temperature change

Zn(s) + Pb2+ (aq) => Zn2+(aq) + Pb(s)

Cu+2

26.00 going down to 25

Pb

Temperature change, color change from blue to colorless, brown solid forms (copper)

Pb(s) + Cu2+ (aq) => Pb2+(aq) + Cu(s)

Mg+2

Pb

None

Pb(s) + Mg2+ (aq) => Mg2+(aq) + Pb(s)

Zn+2

Pb

None

Pb(s) + Zn2+ (aq) => Zn2+(aq) + Pb(s)

Discussion

. A metal is more reactive if it is able to displace another metal’s ions from its aqueous salt solution. From the experiment results, magnesium is the most reactive of the four metals. This is shown by the fact that it displaces all three ions (Zn2+Pb2+ Cu2+) from their respective aqueous solutions, leading to the formation of aqueous magnesium ions. No reaction takes place when magnesium metal is placed in an aqueous solution of any of the three other metals. Zinc displaces both copper and lead, leading to the formation of zinc ions. Lead displaces copper ions, but has no effect on either magnesium or zinc. Copper ions are displaced by each of the other three metals, making it the least reactive of the four. The displacement of copper (II) ions in each instance is evidenced by a change in color of the aqueous solution from blue to colorless due to the loss of copper (II) ions, and formation of a brown solid of copper metal. Thus, the metals rank as follows by order of reactivity: magnesium (most reactive) – zinc – lead – copper (least reactive).