Electrochemical Cells Lab Report

ELECTROCHEMICAL CELLS

Department of Chemistry

Introduction

An electrochemical cell consists of two half-cells. Each half-cell consists of an electrode, and an electrolyte. The two half-cells may use the same electrolyte, or they may use different electrolytes. The chemical reactions in the cell may involve the electrolyte, the electrodes or an external substance (as in fuel cells which may use hydrogen gas as a reactant). In a full electrochemical cell, ions, atoms, or molecules from one half-cell lose electrons (oxidation) to their electrode while ions, atoms, or molecules from the other half-cell gain electrons (reduction) from their electrode. A salt bridge is often employed to provide electrical contact between two half-cells with very different electrolytes—to prevent the solutions from mixing. This can simply be a strip of filter paper soaked in saturated potassium nitrate (V) solution. Other devices for achieving separation of solutions are porous pots and gelled solutions.

Procedure

A Voltaic Cell

1. Two 1 X 3-cm strips, one of copper and one of zinc, were attached to a copper wire with alligator strips. 40mL of 1M CuSO4 solution was placed in a 150 mL beaker and supported in a small porous cup that was nearly filled with 1M ZnSO4, while making sure those two solutions did not mix.

2. The two metal strips were then connected to a voltmeter and the voltage of 1V was read and recorded.

3. This experiment was repeated using 40mL of 2M CuSO4 in a clean beaker and 2M ZnSO4 in a clean porous cup. The voltage was then read and recorded for any differences on the voltage delivered versus the previous experiment.

4. The experiment was then repeated with electrodes that were 0.5 X 3 strips of copper and zinc, and the voltage was read and recorded for any differences that the shorter electrodes may have had.

Electrolytic Cells

1.

a. 1mL of 0.1M NaI solution, 9 mL of water, 1mL of fresh starch and two drops of phenolphthalein indicator were combined...