Oxidation reducation lab PDF

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Chemitry ASUN LAB...

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Oxidation-Reduction Activity Series Hands-On Labs, Inc. Version 42-0186-00-02

Lab Report Assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

Exercise 1: Describing an Oxidation-Reduction Reaction Data Table 1. Redox Reaction of Copper and Silver Nitrate. Initial observations before beginning

Copper: thin squares Silver Nitrate: Clear Liquid

Observations

Cu turning black and bumpy

Observations after 30 minutes

Cu formed crystals fuzzy growth/Cu brown/green

Chemical equation

Cu + 2AgNO3  Cu(NO3)2 + 2Ag

Element that is oxidized

Cu

Element that is reduced

Ag

Spectator ion

Nitrate (NO3^-)

Oxidizing agent

AgNO3

Reducing agent

Cu

Questions A.

Define oxidation, reduction, and oxidation number. Describe how oxidation and reduction affect the oxidation number of an element. Oxidation is the loss of electrons by a substance undergoing a chemical reaction. During oxidation, the oxidation number of the element increases and becomes more positive. Reduction is gain of electrons by a substance undergoing a chemical reaction. During reduction, the oxidation number of the element decreases and becomes more negative. Oxidation is a number assigned to an element in a compound. The number enables us to describe oxidation –reduction reactions, and balancing chemical reaction. Oxidation number increases when a reactant gets oxidized and vice-versa when it gets reduced.

B.

Define oxidizing agent, reducing agent, and spectator ion. Oxidizing agent: the reactant that accepts electrons and oxidizes another one participating in the reaction. Reducing agent: the reactant that donates electron and reduces another one participating in the section. Spectator ion: the reactant that does not get affected during the reaction.

C.

In the reaction of copper and silver nitrate, a new substance appeared in the test tube. Describe the physical appearance of the substance and identify its chemical formula. The Physical appearance was black and solid the new substance is silver metal. The chemical formula is Ag.

D.

Given an activity series in which the most active metals are at the top of the list and the least active metals are at the bottom of the list, would copper be listed above silver or would silver be listed above copper? Support your answer with data from Data Table 1. Silver would be listed below copper. It precipitated out the silver from the silver nitrate solution giving the indication that silver has a higher activity then copper.

E.

Solid copper sulfide and silver nitrate react to form copper (II) nitrate and solid silver sulfide. Write a balanced chemical equation that describes the reaction. Identify the oxidation number of each element in the reaction. (You do not need to include the total contribution of charge.) Is this reaction a redox reaction or a non-redox reaction? Explain your answer. CuS(s) + 2AgNO3(aq)  2Ag25S(s)  +Cu(NO3)2(aq) Oxidation NO- +2 -2

+1

+5 -2

+1 -2

+2 +5 -2

There are no changes in the oxidation state of any of the reactants in the reaction. It is a non-redox reaction

Exercise 2: Creating an Activity Series Data Table 2. Redox Reactions of Copper, Lead, and Zinc. Solid metal

Well ID

Solution

Immediate observations

30 Minute Observations

A1

Pb(NO3)2

No change

No change

A2

Zn(NO3)2

No change

No change

B1

CuSO4

Reddish looking layer of solid forming on metal piece. Blue solution

Not as much blue. Reddish and white colored layers on metal piece.

B2

Zn(NO3)2

No change

No change

C1

CuSO4

Reddish layer of solid. Blue solution

Less blue. Reddish and white colored layers on metal piece.

C2

Pb(NO3)2

Gray colored layer of solid starts to form. Clear solution

Gray color layer of solid formed on the metal.

Cu

Pb

Zn

Data Table 3. Potential Redox Reactions and Chemical Equations. Metal and Metallic Solution

Reaction Occurred?

Chemical Equation

Cu + Pb(NO3)2 Cu + Zn(NO3)2

No No

No Reaction No Reaction

Pb + CuSO4

Yes

Pb+CuSO4->Cu+PbSO4

Pb + Zn(NO3)2

No

No Reaction

Zn + CuSO4

Yes

Zn+CuSO4->Cu+PbSO4

Zn + Pb(NO3)2

Yes

Zn + Pb(NO3)2-> Pb + Zn(NO3)2

Questions A.

List each of the metals tested in Exercise 2. Indicate the oxidation number when each element is pure and the oxidation number when each element is in a compound. Metal

B.

ON in Pure Form

ON in Compound Form

Cu

0

+2

Pb

0

+2

Zn

0

+2

Which of the metals in Exercise 2 was the strongest oxidizing agent? Was there an instance when this metal also acted as a reducing agent? Explain your answer using data from Data Table 3. Copper is the strongest oxidizing agent in exercise two. It doesn’t act as a reducing agent.

C.

Which of the metals in Exercise 2 was the strongest reducing agent? Was there an instance when this metal also acted as an oxidizing agent? Explain your answer using data from Data Table 3. The strongest reducing agent is zinc. It did not act as an oxidizing agent at any point during this lab.

D.

How does ease of oxidation correlate with activity? Do highly active metals tend to donate electrons or accept electrons from other metals? When the activity series for copper, lead, and zinc. Place the most active metal at the top of the list.

E.

Create an activity series for copper, lead, and zinc. Place the most active metal at the top of the list. Activity series for copper, lead, and zinc. Zn Pb Cu

Activity...