Children's chemistry experiments: how we tested chemical kits
As I promised, I continue the story about the experiments that we conducted using the MEL Chemistry experiment kits. The titles are exciting: "Chemical Eraser", "Colored Chemistry" and "Salt Battery". The subscriber of the program (at retail they are not for sale) receives these three sets in November.
We decided to start with "Color Chemistry". There are two experiments in the set, during which the liquid should change its color. With the solution of potassium permanganate everything was possible - in a few minutes it really turned dark green before our eyes, and then it turned orange-brown. Colors "Chameleon" (so called experience), of course, in reality they are not the same as on the experiment card, but they coincide with those on the video.
And here is an experiment enticing by the view of multi-colored cups. "Magic liquid" we did not go as planned. We again (at the insistence of the children) were guided only by the experiment card, did not watch the video, did not read the instructions on the site (“It's more interesting!”). Therefore, water for dilution and staining of substances in 5 cups was poured regular, from the tap (and it was necessary to bottled). And she became not blue, but orange! As I understood from the description, this means that our tap water is somewhat similar in properties to citric acid solution ...
We decided to act with the resulting color. Strangely enough, it turned into red, orange and yellow, green did not work, and in the last cup the blue color suddenly appeared. That is, the acid that we accidentally found in tap water, reacted with sodium carbonate and a neutral solution was obtained, so what?
If you want to turn out beautifully, read the instructions on the site and watch the video - there will be less inaccuracies and errors.
If Color Chemistry is a spectacular, fun, and technically simple experiment, then experience "Salt battery" requires considerable manual dexterity. Last time I wrote about the age of the children for whom the experiments were designed, so not every adult will cope with the scrupulous work in this experiment, and a 12+ child is very desirable here! The graphite powder with manganese oxide is poured into the thin tubule in turn, a graphite rod is inserted, cotton wool is pushed in, zinc powder is poured, and all this is closed with foil balls ... And there are two such batteries! It looks like a puff dessert, not a battery, but the electric current is on and the light is on!
Practical note to many experiences. Often it is required to pour some powder from a vial into a test tube. So, just to turn the vial up is not always the right way: sometimes the contents get stuck on its “hangers”. Maybe this is such a special design, I do not know. We were best at pouring, tilting the vial at about 45 degrees and tapping it lightly.
The explanation of this experiment seemed to me the clearest, the history of the invention of salt batteries was very relevant to the place, and a lot of practical information on their use was liked by the children. The best part is that after a few hours, when the dad showed the battery to the dad who came from work, it worked!
Two points remained unclear to us. First, why should the tube be dipped into a mixture of graphite and manganese oxide before turning it into a battery? And second: how is the “antennae” of the LED and the ends of the wires coming from the batteries attached? We decided not to fasten anything, just put the contacts on each other. The most impressive was the blue LED.
In a set for experiences "Chemical Eraser" Three experiments were waiting for us - the actual “eraser” (which turned out to be liquid!), "Disappearing iodine" and "Diffusion of iodine".
Attention, an important point is missed in the instructions for the experience with an eraser on the site: after applying the decolorizing solution onto the mark left by a ballpoint pen, you have to wait 15 minutes (Section 8, this is reflected on the experiment card). Acetic acid is created during the experiment - do not be alarmed by the corresponding smell, just ventilate the room!
The experience is really impressive - there is no trace of the drawing with a pen. Of course, to correct the grades in the school diary looks rude, but the fact itself! When you “smear” the inscription, do not overdo it with the liquid: literally one or two drops you can gently “smear” the nose of the bubble on the trail of the handle.
The experience in which iodine penetrates into the walls of the jar, and then even with the help of a solvent, does not want to "leave" from there - spectacular, but long: you have to wait a whole day! But the explanation is detailed and understandable (even about the structure of polymers), and the example with the spread of the smell of mandarin is beyond praise! As a result of this experience, you can talk with your child about the occurrence of various stains (on clothes, furniture, wallpaper) to which he is involved, and why it is not possible to remove them. Diffusion!
Well, with "Disappearing iodine" everything is simple - really disappears. The children remembered that they had read about removing iodine spots with raw potatoes - that's just what kind of reaction occurs there, of course, we don’t know.
And a few words about the MEL Chemistry program as a whole - as we managed to see it. In order for a child not just to passively pour-passively, but to understand the meaning of what is happening, the non-chemical parent will have to seriously prepare for the experiments. The description of the experiments (“What happened”) was done in a fun and detailed way, but for me, for example, the child lacks basic knowledge for understanding and subsequent explanation - according to my recollections, chemistry was presented to us in school a little differently. It would be very useful on the site MEL Chemistry dictionary with basic concepts - ion, oxide, valence, etc., ideally - that links to it should be directly from the words in the description of the experiment. While it is necessary to climb in directories on the Internet.
As I immersed myself in the experiments, fragments of school knowledge in chemistry gradually emerge - but all these are fragments, and without a complete picture, the movement from the general to the particular is hard for me personally. Although I suspect that children perceive it differently - precisely as a separate plot, and then from these subjects the whole picture of chemical interrelationships will be formed.
This is also why the age of 12+ is important - if the parents are “not boom-boom” and the child is small, both of them will be enough to make a spectacle (which, of course, is also quite good in the sense of joint leisure). But a 12+ person, if he so desires and has some interest in chemistry (otherwise it’s not worth starting it all up), can figure out the descriptions, and gradually learn to read formulas. In general, it is worthwhile for enthusiastic!