This is an in-class exercise to be used at the end of General Chemistry (II). I use it as a capstone exercise at the end of my second semester genchem course, but it would also make an excellent introductory review exercise at the beginning of a junior level inorganic course. It provides an excellent review of topics from the entire semester (electrochemistry, acid-base, thermodynamics, colligative properties, solution chemistry and calculations) and shows how they are inter-related in a real world application (a car battery).
• A student should be able to dissect the shorthand notation for a voltaic cell and convert that to a balanced redox equation in acidic conditions. • A student should be able to use the Nernst equation to calculate the potential of the battery at non standard conditions. • A student should be able to apply Hess' Law to calculate basic thermodynamic properties for a balanced equation. • A student should be able to calculate concentration of solutions, and to discuss the applicability of these different units. • A student should be able to use his/ her knowledge of colligative properties (both concept and calculation) to discuss the effect of temperature on a battery. • A student should be able to apply his/her knowledge of LeChatelier's Principle to make predictions about the effect changes in conditions will have on the state of a battery.
Since this is an in-class activity, no assessment is typically performed because we go through the solutions during the class period. I have occasionally collected clicker results for some of the numerical questions to encourage students to really work at solving it on their own. The usefulness of the exercise can be measured in the quality of the discussion that is generated.