Oxidation-Reduction (Redox) Reactions Report

Abstract

Redox reactions are crucial not in the field of chemistry but they form a very important part of life of the living organisms. This being a major factor of survival for all living things, we begin this work by introducing the commonly known type oxidation and reduction reactions well known to most of chemists and other scientists.

After setting the basis of subjects, there a part which is dedicated to explaining how chemical reactions are detected as taking placing through instructions of what was done in the work which is further discussed in the paper. Then, we show evidence of redox reactions in the part that following by displaying the result obtained after which detailed information of the reactions are deduced to make the target audience better understand the work accomplished. At the end, we finally pinpoint the major fact established through the carrying out of the experiment.

Introduction

In the field of chemistry, there are many reactions which are performed for the purpose of producing new products, which may be simpler or complex than the original ones depending on the nature of reaction that takes place. Most of the chemical reactions carried out during the synthesis and manufacture of these new products mainly occur through reduction and oxidation reactions simply referred to as redox reactions (Atkins and Loretta, 2007, 356).

Redox reactions are thus very important in the world of chemistry, especially by considering that they occur between and within elements or compounds in their three state of nature. That is, redox reactions may take place with element of the same kind like metal (metal ions) reacting with another type of metal ions as exemplified with silver and copper metals; or redox reactions also involve elements of different states. For instance, burning of substances is a common method known for the production or synthesis of new products, it’s among the redox category of reactions involving the addition and removal of the oxygen element from other elements or compounds (Zumdahl, 2007, 45)

Despite the fact that combustion reactions/ synthesis are widely known as representative of the redox reaction group, the transfer of electrons and hydrogen from one compound or element to another is also another form redox reaction, which more specifically are represented as displacement reactions, and are more advanced and sophisticated as compared to combustions (Olmsted, 2005, 56). Similar to combustion, elements in the same period or group may show similarities or differences in their displacement ability, hence, becoming important in synthesis/production and separation techniques for compounds and certain elements. It is from this point of view, on which the current experiment is based on, mainly to get the insight of the reaction trends of elements and ions of various elements belonging to the same periodic groups of IV and VII.

Aim/Objective

The objective of this study was to explore and discover the trends of reducing and oxidizing strength of elements in the same groups, compare the phenomenon trends of redox reactions of metal-metal with those of gaseous elements in groups VIIA elements, try physically through observation means identify the products of the redox reactions after establishing their balance half cell redox reaction equations.

Equipment and Methodology

Part 1: Reaction of metal with metal ions

Three small clean stripped pieces of Zinc were each placed in a test tube, and 1.5 ml solution of Zinc, Copper and lead were added each to one of the three test tubes containing the pieces of zinc. The mixtures of the contents in the test tubes were observed for any reaction for about 5-10 minutes and the observations were recorded down. The procedure above was repeated using copper and lead in place of small cleaned piece of stripped Zinc.

Part 2: Dissolution of Non-metals with Non-metal ions

Approximately 1.5 ml of chlorine (Cl₂), bromine (Br₂) and iodine (I₂) were placed in separate test tubes. To each of the three test tubes, it was then added about 1 ml of dichloromethane (CH₂Cl₂) , stoppered and shaken for fifteen seconds. Observations were made and recorded down.

Reaction of Non-Metals with Non-Metal Ions

Approximately 1.5 ml of 0.1 M of NaBr and NaI were each placed in a test tube, and 1 ml of appropriate solvent added. To each of the test tubes, 0.5 ml of Cl₂ was added, stoppered and shaken for 15 seconds. Observations were made and color changes of the solvent phase were accordingly recorded and the results were compared with those obtained in iii above. The above procedure steps were repeated using 0.1 M NaI with addition of approximately 5-drops of Br₂ to each test tube containing the solutions and solvent. Steps I-IV was once more repeated using 0.1 M NaCl and NaBr with additions of 5-drops of I₂ to each of the test tubes with the contents.

Results

A diagram photograph showing the result obtained of the reaction of non-metals with non-metal ions.

As seen from the diagram, there are certainly distinct differences of colors of the various experimental setups with different elements and ions. Based on the three experimental setups of the different elements of chlorine, bromine and iodine, the layers of separation becomes more distinct and conspicuous as one moves from iodine and bromine to chlorine. There is less and almost no physical indication of some reaction(s) taking place in iodine setups test tubes with others, but there augmented indication of a reactions taking placing between chlorine with the other two elements of Iodine and bromine. The rate of change of color between the reacting elements and ions are good indicators of rate in which the chemical reactions of oxidations and reductions are taking place (Williams, 1996, 198).

Answers and Question Discussion

1. From experiment performed, Zinc metal was oxidized by both copper and lead metal ions. The copper metal was oxidized by only lead metal ions, whereas lead was not oxidized by either of the above two metal ions. That is, both Zinc and copper ions couldn’t oxidize lead metal (Bauer et al, 2006, 893)
2. Half equations for the oxidation reactions

Zn=Zn⁺² + 2e

Cu=Cu⁺² + 2e

Reduction half-reactions:

Pb⁺² + 2e = Pb

Cu⁺² + 2e =Cu

Overall redox reaction:

Zn +Pb⁺² = Zn⁺² +Pb

In the experiment performed for the halide elements/ non-metals with non-metal ions, the iodine ions (I^-1) were oxidized by both chlorine and bromine elements, while the chloride (Cl^-1) ions were not oxidized by the two elements.

3. Oxidation half-reactions

2I^-1 = I₂ + 2e

2Br^-1= Br₂ + 2e

Reduction Half-reactions:

Cl₂ + 2e = 2Cl^-1

Br_{2 +} 2e = 2Br—¹

Overall redox reaction:

2I^-1 + Cl₂ = I₂ + 2Cl^-1

Conclusion

Depending on the results of the experiment and literature gained from numerous other sources related to the experiment that was carried out, we conclude that oxidation and reduction reactions occur with reactions carried out with metallic and non-metallic elements in the same group in the periodic table. It was however noted that oxidation occurs at slow phase down the group of metallic elements whereas it increases with the non-metallic elements of group VII A. On the hand, reduction increases moving up the group VIIA elements of halogens, while it decreases with metallic elements in group IVA of the periodic table.

References

Atkins, P. and Loretta, J. 2007. Chemical Principles: The Quest for Insight. W H Freeman & Co

Bauer, R., Birk, J. and Marks, P. 2006. Student Solutions Manual to Accompany A Conceptual Introduction to Chemistry. NY: McGraw-Hill

Olmsted, J. 2005. Chemistry, Student Study Guide. New York: John Wiley & Sons

Williams, G. 1996. Chemistry: The Molecular Science. Jones & Bartlett Publishers

Zumdahl, S. 2007. Chemical principles. Houghton Mifflin