Laboratory work

 

Oxidation and Reduction reactions

 

Purpose: To investigate and compare the relative ease of oxidation and reduction of copper, lead, and zinc.

 

Definations: Reduction, oxidation, single replacement reaction, net ionic reaction, activity series.

 

Materials:

·         spot plate

·         zinc powder

·         copper pieces

·         lead pieces

·         0.1 M copper(II) nitrate

·         0.1 M lead(II) nitrate

·         0.1M zinc nitrate

 

Safety:

·         Wear safety goggles.

·         Copper and lead compounds are toxic. Wash your hands at the end of the lab.

 

Procedure:

As you perform the experiment, record your observations in Table 1.

1.      Place each combination of metal and metal ion into the wells of the spot plate as laid out in Table 1. Use only one piece of copper, one piece of lead, and a few granules of zinc powder for the metal samples. Use only three drops of each metal ion solution. Do not contaminate the solutions by mixing droppers.

2.      Allow the spot plate to stand undisturbed for 10 minutes.

3.      Record your observations in Table 1, briefly describing evidence of any reaction. If no reaction is visible, write NR.

4.      To clean up, throw the metal pieces in the marked container on the back bench, and rinse the solutions on the spot plate in the sink with plenty of water. Clean the spot plates and return to the back bench.

 

Table 1. Observations of Reactions

 

Cu+2

Pb+2

Zn+2

Cu(s)

 

 

 

Pb(s)

 

 

 

Zn(s)

 

 

 

 

Questions:

1.      State the most important safety concern in this lab and the required precaution you took.

2.      Write balanced net ionic equations for any reactions that you observed.

3.      Which metal was oxidized by both of the other two metal ions?

4.      Which metal was not oxidized by either of the other metal ions?

5.      List the metals in order of most easily oxidized first. Compare this order to that in Regents Table 1.

6.      Write balanced half reactions for the reduction of the halogens, F2, Cl2, Br2, and I2. List these in the order of most easily reduced first (you will need to refer to Regents Table J).

7.      Many metals are oxidized by aqueous solutions of acids (such as HCl) to produce hydrogen gas and metal ions. Based on the results of this lab, which of the three metals studied in this lab would be most easily oxidized by HCl? Write a balanced equation.

8.      Honors: What was the most probable source of error that would lead to incorrect observations?