Write redox equations and describe the transfer of electrons occurring in a reaction
· Compute voltages and concentrations for a given Galvanic cell using the Nernst Equation
· Identify the difference between standard and non-standard concentrations in a Galvanic cell
· Use observed cell potentials to determine where a reaction fits in the activity series
· Communicate your findings as a formal lab report
Batteries: Portable Chemistry
You’re already familiar with the ubiquitous nature of batteries in our society—you’re probably reading this lab manual on a laptop or computer, powered by a chemical battery. And your phone in your pocket, the watch on your wrist, the calculator on your desk, all use chemically-powered batteries. Some of these are rechargeable, and some aren’t, but they all work on the principles of a completed circuit and a spontaneous redox reaction. The drive of the chemical reaction powers your devices.
A reduction-oxidation (redox) reaction is one where electrons are transferred from one species to another in the process of making the products. If we physically separate the electron donor (the anode) and the electron recipient (the cathode), connecting them by a wire for electron flow and a salt bridge to rebalance the ionic charge, we can harness the flow of the electrons to do work as they make their way over from the anode to the cathode. Because the redox reaction chosen is spontaneous, the process will begin to occur as soon as we complete the loop. This setup is called a Galvanic cell (see Figure 1).
The voltage resulting from a Galvanic cell depends on a few factors, such as the temperature and the number of electrons involved in the reaction. These variables are all related to one another by the Nernst Equation:
We’ve discovered five new elements (!) that have been shown to be metals that undergo redox reactions. A discovery of these new materials could revolutionize batteries! These metals need characterized, and we’re asking you to investigate them and rank them from most reactive to least reactive. You’ll report back your findings as a formal lab report.