The lab was a success as I watched startled students produce the so-called barking dog sound as they combusted the hydrogen gas in their inverted test tubes.
I have used several different versions of the Silver Mirror or Tollen's Test lab. I am sharing the method that has proven to be the most reliable for me. The solutions should be made fresh, the directions must be followed closely and timing is very important. I like the fact that relatively small amounts of the chemicals are required, but as always you must be vigilant with safety precautions.
My IB seniors are just wrapping up our unit on electrochemistry and redox. This has always been a challenging topic within the IB curriculum. Admittedly, electrochemistry has not ever been my strong suit either, so this year I aimed to strengthen the unit with two additional demonstrations.
The chemistry of silver and the process in which silver becomes tarnished is explored. Take a new look at an old JCE Classroom Activity.
You can perform an orange to black chemistry demonstration using materials commonly found in stores. The reaction appears to be similar to the Old Nassau reaction, but uses greener reagents. This is a great demonstration to do around Halloween time.
In this Activity, students investigate the process of rusting by studying the oxidation of steel nails in a gel using supermarket chemicals. An indicator makes the presence of Fe3+ produced by the oxidation visible. Factors that accelerate or retard the rate of iron oxidation are studied.
In this Activity, students compare the combustion of different substances such as a glowing wooden toothpick and lit birthday candle in air, oxygen, exhaled breath, and carbon dioxide environments. The oxygen and carbon dioxide are generated from supermarket chemicals. This Activity can be used to explore the chemistry of oxygen and combustion.
In this Activity, students construct a simple battery from aluminum foil, saltwater, and activated charcoal. The battery can power a small motor or light. This Activity demonstrates oxidation and reduction reactions, which are integral parts of battery chemistry.
In this Activity, students determine the concentration (percent volume) of oxygen in air. They place small quantities of fine steel wool into a test tube that is then inverted in a beaker of water. Oxygen in the trapped air reacts with the iron to form rust. The Activity ties in well with atmospheric chemistry.
In this Activity, students make a chemical clock using chemicals found in the supermarket: vitamin C tablets, tincture of iodine (2%), hydrogen peroxide (3%), and liquid laundry starch. They investigate what happens to the speed of the clock when the reactant solutions are made more or less dilute.