Materials Included In Kit

Additional Materials Required

Safety Precautions

The lead nitrate solution is moderately toxic by inhalation and ingestion, a strong oxident and a possible carcinogen. The copper(II) sulfate solution is toxic by ingestion. Silver nitrate is a highly toxic corrosive solid that will cause burns. Avoid contact with eyes and skin. Sulfuric acid is severely corrosive to eyes, skin and other tissue. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Wash hands thoroughly with soap and water before leaving the laboratory. Please consult current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. The lead nitrate solution should be treated according to Flinn Suggested Disposal Method #27f. The silver nitrate solution should be precipitated according to Flinn Suggested Disposal Method #11. Sulfuric acid should be neutralized according to Flinn Suggested Disposal Method #24b. All other solutions may be flushed down the drain with excess water according to Flinn Suggested Disposal Method #26b.

Teacher Tips

• The silver nitrate concentration can be diluted to 0.05 M or less.
• Have the student dry the metal strip; then clean it with a piece of steel wool after each test.
• Cut metal strips to accommodate your class size.
• Using a 5 M concentration of sulfuric acid will allow the displacement of hydrogen (gas bubbles) to be more visible.
• Place two Beral pipets with each solution and have students fill their wells about ¼ full with the solution.
• Tape or rubberband a small test tube to the solution bottles to provide a convenient container to place the Beral pipets for each solution.

Sample Data

Answers to Questions

1. What element would you consider to be the most active? Why?

   The most active element is magnesium since it replaced all the other elements used in the experiment.

2. What element would you consider to be the least active? Why?

   The least active element is silver since it was replaced by all the other elements used in the experiment.

3. Using your data, does copper replace zinc?

   No, copper does not replace zinc since there was no reaction taking place.

4. Using your data, which element is more active, copper or zinc?

   Zinc is more active than copper since zinc replaced 4 elements whereas copper replaced only 1 element, silver.

5. Which element has the greater tendency to retain electrons, copper or zinc?

   Copper has the greater tendency to retain electrons since it only replaced 1 element (silver), whereas zinc replaced 4 elements.

6. Which element is more active, copper or hydrogen? Why?

   Hydrogen is more active than copper since copper did not replace hydrogen in the experiment.

7. Which element has the greater tendency to retain electrons, copper or hydrogen?

   Copper has the greater tendency to retain electrons since copper did not replace hydrogen.

8. Write a balanced equation for the reaction that took place between the copper metal and the silver nitrate solution.

   Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)

9. Write a balanced equation for the reaction that took place between the magnesium metal and the sulfuric acid.

   Mg(s) + H₂SO₄(aq) → MgSO₄(aq) + H₂(g)

10. Elements that tend to give up electrons most easily are said to be most electropositive. Are there any elements in this experiment which are more electropositive than silver? List them.

    Magnesium, Zinc, Lead, Hydrogen, Copper

11. Using your data, list the elements in their order of activity (most active to the least active).

    Magnesium, Zinc, Lead, Hydrogen, Copper, Silver

Introduction

In this experiment, several chemical reactions will be examined. From the observations, a list of six elements in their order of activity beginning with the most active element down to the least active element will be constructed.

Concepts

• Order of activity
• Oxidation state

Background

The oxidation state of an atom is zero. The ease with which this oxidation state is changed by giving up electrons indicates the relative activity of the atoms of this element. Compare the oxidation numbers of sodium and hydrogen on the left side of the equation (reactants) to that of the sodium and hydrogen on the right side of the equation (products) in the Equation 1.

Notice that the oxidation numbers of sodium and hydrogen have changed. In its free state, sodium has an oxidation number of 0. As the chemical reaction takes place, sodium gives up an electron to hydrogen in the water molecule causing the sodium to change its oxidation number from 0 to +1 as seen in the sodium oxide molecule. Since sodium gave up its electron more easily than hydrogen, sodium is considered a more active element than hydrogen.

Observing spontaneous reactions such as that symbolized in Equation 1, allows scientists to devise a list of elements in their order of activity. Using such a list can help one predict whether a chemical reaction will take place or not take place.

Materials

Safety Precautions

The lead nitrate solution is moderately toxic by inhalation and ingestion, a strong oxidant and a possible carcinogen. The copper(II) sulfate solution is toxic by ingestion. Silver nitrate is a highly toxic, corrosive solid that will cause burns. Avoid contact with eyes and skin. Sulfuric acid is severely corrosive to eyes, skin and other tissue. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Wash hands thoroughly with soap and water before leaving the laboratory.

Procedure

1. Using a 24-well reaction plate (see Figure 1), place about 1 mL (fill the well about ¼ full) of each solution into separate wells—magnesium sulfate in well A1, sulfuric acid in well A2, copper(II) sulfate in well A3, lead(II) nitrate in well A4, silver nitrate in well A5 and zinc sulfate in well A6.
   {12567_Procedure_Figure_1}
2. Clean a strip of magnesium metal with some fine steel wool. Place one end of the strip into well A1 for a few moments, then remove. Is there any displacement reaction? Record the observations.
3. Dry and clean the magnesium strip and repeat with wells A2 through A6. Rinse metal strips with water and dry thoroughly before placing strips into the next well.
4. Repeat this process using strips of copper, zinc, and lead. Record the observations after each test.
5. See instructor for disposal procedures.

Student Worksheet PDF

12567_Student1.pdf