How do you prepare a 0.1 M oxalic acid solution for a galvanic cells lab?

Weigh 6.304 g of oxalic acid dihydrate and transfer it to an Erlenmeyer flask. Add 500 mL of deionized water, then stir until homogeneous. Use a powder funnel to transfer the solution to a labeled polyethylene bottle and store it in the instructor's hood. Handle oxalic acid with caution as it is corrosive.

What materials are needed to prepare a salt bridge for a galvanic cell experiment?

Cut string into 2-inch pieces, with three pieces needed per group. Soak the strings in a 0.1 M potassium nitrate solution for one hour before the lab begins. This prepares the salt bridge, which maintains electrical neutrality between the two half-cells in the galvanic cell.

How should metal electrodes be prepared before use in a galvanic cells experiment?

Cut copper sheet into 2 x 9 cm pieces, zinc sheet into 2 x 6 cm pieces, and silver sheet into 2 x 6 cm pieces. Store each metal type in labeled beakers corresponding to unknown numbers. Clean metal surfaces with emery paper cut into 1 x 2 inch pieces to remove oxidation before assembly.

What is the correct procedure for preparing unknown solutions in a galvanic cells lab?

Prepare 0.05 M zinc sulfate by weighing 3.6 g and dissolving in 250 mL deionized water. Prepare 0.22 M silver nitrate by weighing 9.34 g and dissolving in 250 mL deionized water. Divide each solution into two brown glass bottles labeled with corresponding unknown numbers and store in the instructor's hood.

What equipment should be set up at each lab station for a galvanic cells experiment?

Each station requires a multimeter with leads, alligator clips, glass thermometer, 6-well reaction plate, forceps, volumetric flasks, graduated cylinders, beakers, glass funnels, and a 20-mL volumetric flask. These tools enable students to measure solutions, monitor voltage, and assemble electrochemical cells for data collection.

How do you prepare the potassium nitrate solution for the salt bridge?

Weigh 2.53 g of potassium nitrate and transfer to a flask. Add 250 mL of deionized water and stir until homogeneous. Transfer the 0.1 M solution to a labeled glass bottle and store in the instructor's hood. Use this solution to soak salt bridge strings one hour before the lab.

What safety and waste management procedures are required for a galvanic cells lab?

Wear appropriate personal protective equipment including a lab coat, chemical splash goggles, and gloves. Handle oxalic acid with caution as it is corrosive. Dedicate a 20-L container for heavy metal waste and ensure it is accessible in the hood for safe disposal of all metal-containing solutions and materials.

Galvanic Cells

Concepts Instructor Prep Student Protocol

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An electrochemical reaction is a process where electrons are transferred between two substances, with one losing electrons and the other gaining them. When a substance loses electrons, we say that it has undergone oxidation or that it has been oxidized. When it gains electrons, we say that it has undergone reduction or has been reduced. To help you distinguish between the two, remember the phrase 'oil rig,' which stands for oxidation is losing, reduction is gaining. Some electrochemical reactions occur spontaneously, which we can study in a galvanic cell.

The galvanic cell has four main parts. First, there are two metal electrodes, each of which is immersed into a different electrolyte solution. The solutions consist of the ions needed for the half-reactions, either the oxidation or reduction reaction, that occur at each electrode. The solutions are connected by a salt bridge, which enables the flow of ions and maintains the charge neutrality of the solutions. The electrodes are connected by an external circuit, which the electrons travel through during the reaction.

The anode is the electrode that gives up electrons in the reaction or is oxidized. The cathode is the electrode that gains electrons and is reduced. To help you distinguish between these two labels, remember the phrase 'red cat,' since reduction occurs at the cathode.

So how do we know which metal acts as the anode and which acts as the cathode? We can use the standard electrode potential of the metal, which is a measure of the metal’s tendency to lose electrons. A more negative electrode potential means that the metal has a higher tendency to lose electrons. Electrons always flow from the metal with the lower standard potential to the metal with the greater standard potential.

In a galvanic cell, electrons flow from the anode to the cathode, thus the anode is the metal with the lower standard potential, and the cathode is the metal with the higher standard potential. As the electrons travel between the two electrodes, an electric potential is measured. The magnitude of the voltage produced is equal to the standard potential of the cathode minus the standard potential of the anode.

So, if two metals with similar standard electrode potentials are used in the galvanic cell, like lead and tin, for example, the magnitude of voltage produced will be low. If the metals have different standard potentials, like silver and magnesium, the voltage produced will be high.

In this lab, you will construct a galvanic cell using two metal electrodes and measure the potential produced as the oxidation and reduction reactions occur. You'll then identify unknown metal electrodes using known standard potentials and determine the magnitude of the voltage produced.

At the end of this lab, students should know...

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What is electrochemistry?

Electrochemistry is a branch of chemistry that studies the relationship between a chemical reaction and electrical energy.

What are the key components of an electrochemical cell?

An electrochemical cell consists of a reaction chamber (or chambers) containing electrolyte solution(s), a salt bridge, and two conductive electrodes (the anode and cathode) that are connected electrically...

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