So I had a terrible time with this chapter (Chapter 19: Oxidation-Reduction Reactions in Modern Chemistry) and spent a lot of time on youtube trying to get a grip on this stuff.  I realized part of my problem was that I didn’t understand the oxidation states well enough so I backed up a bit and these videos by Khan Academy helped me the most.

Tyler DeWitt has a pretty good video as well:

Most of the labs for this subject involve watching iron wool rust over several days (lab X-2: Observe the electrochemical Oxidation of Iron)… not exactly conducive to a two hour class.  So I had my son set up one of them yesterday so the students could just observe the results in class today and then we did lab IV-1: Observe Oxidation States of Manganese, from the home scientist’s chemistry kit manual, CK01A. The first lab was just observing a bit of iron wool in 6 different test tubes with various combinations of water, salt and oxygen available to the wool.IMG_9511

The second lab involved looking at different oxidation states of manganese by putting some in 4 different wells of a reaction plate along with some other chemicals.  This was a nice short lab (only 4 wells!) and you get some significant color changes (see photo below) and even a precipitate in one.IMG_9515IMG_9522

Besides these two labs I also happened to have a chemiluminescence kit which contains luminol solution and hyrdogen peroxide.  Luminol emits light when its oxidized.  I poured approximately 20 ml of luminol into a small beaker and then used a dropper to squirt hydrogen peroxide (Salon Care 40 volume clear developer, 40% hydrogen peroxide, not the weaker stuff that came with the kit) into the beaker – this is done in a very dark room – and the solution glows a very nice blue for a minute.  It probably would have been brighter if my solutions hadn’t been so old. I got this kit a year or two ago and the box says it has a shelf life of a year.
I also spent about 20 minutes lecturing on oxidation states and going over examples from the textbook on how to figure out oxidation states and whether or not a reaction was a redox reaction or not.

 

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