Electrochemical Measurement and Batter Report Galvanic Cell Experiments (Individ

Question

Electrochemical Measurement and Batter Report Galvanic Cell Experiments (Individual work) 1. Write a balanced equation for all ten redox actions you measured. Circle the metal that served as the cathode in each reaction. 2. the theoretical value of AEcell for each reaction by using the Nernst equation, a table of standard reduction potentials, and the actual concentra- tions of the solutions used. 3. Compare these theoretical cell potential differences with those you actually measured and calculate the percentage error for each cell. Comment on pos- sible sources of error in your measurements Answer the following questions: 4. a. For one pairing that initially gave a negative voltage reading, write the redox equation, identify the anode and cathode, and give the direction of flow of electricity in the external circuit. b. What is the purpose of the KNO3 salt bridge? c. A galvanic cell cannot generate electricity forever. List two chemical rea- sons you can think of for why a galvanic cell may go "dead. Galvanic Cell Experiments (Group Work) Discuss with your group the best way to determine the ordering of the five metals, from the one that makes the best cathode to the one that is the worst. Include this listing in your lab report. Construction of Batteries Include a labeled drawing of your team's connected batteries and the total Aecell. How did you connect the cells in order to increase the overall voltage? Be specific and label your drawing. Was this enough energy to power a light bulb (or some other device)? If not, suggest what you could do to light the bulb. Construction of an Electrode 1. For your final report, include a sketch of your electrode assembly. 2. Briefly list and discuss any problems you encountered with the procedure

Explanation / Answer

4.b Salt Bridge:

The sole purpose of the Salt bridge is to maintain the electrical neutrality within the internal circuit which prevents the cell rapidly running its reaction to equilibrium. If the salt bridge is not present in the cell, the solution in one-half would accumulate negative charge and the solution in the other cell will develop positive charge as the reaction proceeds which prevents further reaction and in turn prevents the electricity production.

The reason for KNO3 is it won't dissociate into respective ions and an inert to the solutions.

4.C The galvanic cell cannot generate the electricity forever because the anode can be fully oxidized or the cathode solution is depleted

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

consider the above reaction the solid zinc converts to ions whereas the copper ions turn to solid copper. The most important part of the reaction is the electron from the zinc should travel across the wire and meet copper ions to convert into solid copper. so as the reaction proceeds the solid zinc by losing electrons will convert to ions. So if no solid zinc no flow of electrons so no electricity.

for the same reaction the copper can be replaced by silver, the above explanation holds good.

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