If one weren't going for nostalgia, what chemicals would one put in a modern chemistry kit?
The thing about chemistry, is people who aren't chemists think its all about randomly mixing solutions, so the more chemicals the better.
The actual metric for doing interesting reactions is the number of tools, measurement devices, and apparatus you have. The actual chemicals are almost secondary.
I really enjoyed my undergrad quant class. So a "kit" that would entertain me would involve a ridiculously precision balance / scale, and a spectrophotometer, and a chemistry desiccant / dehydrator vessel thingy and several burettes and graduated cylinders. And the usual array of glassware. Vacuum sep funnel, distillation set, that kind of thing. Oh and I got a huge kick out of electrochemical machinery, I mean at least a precision pH meter but more advanced stuff would be cool. I'm not asking for an NMR or a FTIR spectrometer but who knows what a devoted makerspace could pull off.
Given that kind of gear listed above, I could find chemicals laying around a perfectly normal kitchen or basement to entertain me.
Number and type of chemical is a bad metric. Its like saying the best CPU to program on is the one with the largest instruction set, so a IBM360 is precisely exactly 9.1244 times "better" than a PDP-8. Well it just doesn't work that way. On the other hand a metric of tools and apparatus actually is a pretty good metric.
Its like giving a kid who wants to be a chef an easy bake oven and some prepak mixes. It technically involves cooking, so ...
Or giving a kid who wants to learn about computers an ipod. It does have a CPU inside, doesn't it?
I basically listed what I remember of my lab drawer contents from undergrad quant class. I could see having a lot of fun with less stuff.
Another aspect of hacking / startup / makerspace type activities is making a moderately crude instrument. For example a spectrophotometer with bad but usable specs could probably be made as an arduino shield using a light tight box, an incandescent bulb, a log converter feeding the A/D of the arduino, and a glass prism sitting on a servo controlled by the arduino. And some software.
Or instead of burrets, a digital model using a syringe (no needle needed) and a screw and nut hooked up to a stepper motor driven by arduino. So given a syringe of 1M vinegar or whatever you can squirt out any precision volume.
A PH meter shield for an arduino sounds too simple and obvious to even mention. There are more elaborate potentiometer systems where you measure the voltage required to shove a certain current thru a solution and so forth, stuff I don't remember as well.
As far as budget goes, I don't think you can do "real" chemistry without at least a decent scale and some kind of volumetric measurement tool (a grad cylinder if nothing else? A set of volumetric flasks?)
If you insist on "chemistry without numbers" you may as well just mix different colors of kool aide powder for all you'll learn.
I was given something very similar to this as a kid: http://www.amazon.com/Elenco-MX-907-200-Electronic-Project/d... (in fact, I think it was that, 20 years ago!)
It didn't teach me anything about electronics, I was too young to really grasp what I was doing. It taught me that with sufficient knowledge you can make something out of individually useless bits of electronics.
You're right to be more demanding of your undergrad quant class but this might be just the thing to get your 8 year old niece/nephew interested in science.
I'm just thinking of the first time I saw a piece of sodium dropped in water. So I can imagine that just because its a waste at the professional and real world level doesn't mean it's necessarily a waste at the toy level.
But as for this specific chemical I have no idea if this is true about it or not.
You probably mean sodium for the first, or vinegar for the second. Although neither are harmful the way carbon tet is.
As far as letting noobs play with dangerous stuff for training (or maybe Darwinian selection?) thinking back to my undergrad years the worst stuff we messed with for training purposes was various ionization states of chromium, lead, and mercury. We did at least have multiple marked hazmat buckets, didn't just flush down the drain. That was a long time ago and that kind of stuff might not be acceptable labwork in 2013.
If you ever get to work with aqueous chromium some of the ionization states are beautiful. Incredibly toxic, sure, but you can see why people wanted to use them in paints.
The big risks come when you huff it, which people used to do because it gives you a high. It just also happens to melt your liver.
But if your standard for danger is "unsafe when huffed", then most things in this set are pretty nasty. It's all a matter of perspective.