Assignment This week you will perform an electroplating experiment by watching videos and recording data while you watch. The experimental procedure and video links are all contained in this document. You will plate out copper on a brass key, then compare the mass of copper deposited on the key with the theoretical amount of copper that should have been deposited using Faraday’s Law. At the end of the experiment you will complete the Data Analysis and fill in the Data Table and turn these pages in.

Your grade for this experiment will be determined as follows:

1.      Pages Turned in on time: 10%, the due date for this is May 3rd at 11:00PM.

2.      Score on Data Analysis Pages turned in: 90%

The Chem 192 Team 

Electroplating of Remote Learning Lab Templates 

In this experiment, you will conduct, observe, and measure the process of electroplating. This process is used to deposit a layer of metal, such as chromium, copper, or gold, onto another metal. As a commercial process, electroplated coatings are used to improve appearance, resist corrosion, or improve hardness of metallic surfaces. This experiment describes one method of producing a copper coating on a brass key or other suitable metallic object.

You will prepare an electrolytic cell by using a copper strip as the cathode (positive terminal) and a brass key as the anode (negative terminal). The electrodes are immersed in a solution containing acidified copper (II) sulfate. As you apply a potential to the electrodes, the net effect will be a transfer of Cu atoms from the copper strip to the surface of the brass key via the solution.

The stoichiometry of the deposition process is expressed in equation form below.’

I is the current in amperes(note that an amp is a couloumb per second; t is the time that the current is applied in seconds; MM is the molar mass of the element that is deposited; n is the number of moles of electrons/mol; and 96,500 is ₣, the Faraday constant which is the linkbetween coulombs and moles of electrons.

The units work out as follows

In this experiment you will be plating out copper from CuSO4 so the deposition process is

                                                                        Cu²⁺ +2e  ®  Cu(s)

From this you can see that the stoichiometry is such that 2 moles of electrons are required to deposit one mole of copper.

Figure 1. The electroplating apparatus

OBJECTIVES of Remote Learning Lab

In this experiment, you will

·         Prepare and operate an electrochemical cell to plate copper onto a brass surface.

·         Measure the amount of copper that was deposited in the electroplating process.

·         Calculate the amount of energy used to complete the electroplating process

PRE-LAB ASSIGNMENT of Remote Learning Lab

·         Review your MSDS for Sulfuric Acid and Copper(II) Sulfate, note what pages they are on in your notebook.

·         Review the following sections in your textbook 19.9, especially the example problems

·         Possible Pre Lab questions

o   Write the oxidation and reduction half-reactions for this electroplating experiment.

o   Example Problem 19.21,22,23 and practice problems 19.21,22,23 in your textbook (p.860-864)

MATERIALS of Remote Learning Lab

PROCEDURE of Remote Learning Lab

Turn in this page and the next one containing Data Table and Data Analysis

DATA TABLE

DATA ANALYSIS

1.      Calculate the number of seconds that the current was flowing from the reading on the stop watch? 

1.      Calculate the number of coulombs of charge passed through the electrolytic cell.  Recall that current (amps)  x time (secs)  =  Coulombs

1.      Calculate the theoretical number of grams of copper that should have plated out onto the brass key using Equation

 

1.      Calculate the actual number of grams of copper that plated out from your mass data. 

1.      Calculate the percent yield of copper.

1.      Write the oxidation and reduction half-reactions for this process.

Oxidation half-reactions

Reduction half-reactions