Tag Archives: bases

Toxic chemistry you can do at home

I got my start on science working with a 7 chemical, chemistry set that my sister got me when I was 7 years old (thanks Beverly). The chemicals would never be sold by a US company today — too much liability. What if your child poisons himself/herself or someone else, or is allergic, or someone chokes on the caps (anything the size of a nut has to be labeled as a hazard). Many of the experiments were called magic, and they were, in the sense that, if you did them 200 years earlier, you’d be burnt as a witch. There were dramatic color changes (phenolphthalein plus base, Prussian Blue) a time-delay experiment involving cobalt, and even an experiment that (as I recall) burst into fire on its own (glycerine plus granulated potassium permanganate).

Better evil through science. If you get good at this, the military may have use of your services.

“Better the evil you know.” If you get good at this, the military may have use of your services. Yes, the American military does science.

Science kits nowadays don’t do anything magically cool like that, and they don’t really teach chemistry, either, I think. Doing magical things requires chemicals that are reasonably reactive, and that means corrosive and/or toxic. Current kits use only food products like corn-starch or baking soda, and the best you can do with these is to make goo and/ or bubbles. No one would be burnt at the stake for this, even 300 years ago. I suppose one could design a program that used these materials to teach something about flow, or nucleation, but that would require math, and the kit producers fear that any math will turn off kids and stop their parents from spending money. There is also the issue of motivation. Much of historical chemistry was driven by greed and war; these are issues that still motivate kids, but that modern set-makers would like to ignore. Instead, current kits are supposed to be exciting in a cooperative way (whatever that means), because the kit-maker says so. They are not. I went through every experiment in my first kit in the first day, and got things right within the first week — showing off to whoever would watch. Modern kits don’t motivate this sort of use; I doubt most get half-used in a lifetime.

There are some foreign-made chemistry sets still that are pretty good. Here is a link to a decent mid-range one from England. But it’s sort of pricy, and already somewhat dumbed down. Instead, here are some cheaper, more dangerous, American options: 5 experiments you can do (kids and parents together, please) using toxic household chemicals found in our US hardware stores. These are NOT the safest experiments, just cheap ones that are interesting. I’ll also try to give some math and explanations — so you’ll understand what’s happening on a deeper level — and I’ll give some financial motivation — some commercial value.

1) Crystal Drano + aluminum. Crystal Drano is available in the hardware store. It’s mostly lye, sodium hydroxide, one of the strongest bases known to man. It’s a toxic (highly poisonous) chemical used to dissolve hair and fat in a drain. It will also dissolve some metals and it will dissolve you if you get it on yourself (if you do get it on yourself, wash it off fast with lots of water). Drano also contains ammonium nitrate (an explosive) and bits of aluminum. For the most part, the aluminum is there so that the Drano will get hot in the clogged drain (heat helps it dissolve the clog faster). I’ll explain the ammonium nitrate later. For this experiment, you’re going to want to work outside, on a dinner plate on the street. You’ll use additional aluminum (aluminum foil), and you’ll get more heat and fun gases. Fold up a 1 foot square of aluminum foil to 6″ x 4″ say, and put it on the plate (outside). Put an indent in the middle of the foil making a sort of small cup — one that can stand. Into this indent, put a tablespoon or two of water plus a teaspoon of Drano. Wait about 5 minutes, and you will see that the Drano starts smoking and the aluminum foils starts to dissolve. The plate will start to get hot and you will begin to notice a bad smell (ammonia). The aluminum foil will turn black and will continue to dissolve till there is a hole in the middle of the indent. Draino

The main reaction is 2 Al + 3 H2O –> Al2O3 + H2; that is, aluminum plus water gives you aluminum oxide (alumina), and hydrogen. The sodium hydroxide (lye) in the Drano is a catalyst in this reaction, something that is not consumed in this reaction but makes it happen faster than otherwise. The hydrogen you produce here is explosive and valuable (I explain below). But there is another reaction going on too, the one that makes the bad smell. When ammonium nitrate is heated in the presence of sodium hydroxide, it reacts to make ammonia and sodium nitrate. The reaction formula is: NH4-NO3 + NaOH –> NH3 + NaNO3 + H2O. The ammonia produced gives off a smell, something that is important for safety — the smell is a warning — and (I think) helps keep the aluminum gunk from clogging the drain by reacting with the aluminum oxide to form aluminum amine hydroxide Al2O3(NH3)2. It’s a fun experiment to watch, but you can do more if you like. The hydrogen and ammonia are flammable and is useful for other experiments (below). If you collect these gases, you can can make explosions or fill a balloon that will float. Currently the US military, and several manufacturers in Asia are considering using the hydrogen created this way to power motorcycles by way of a fuel cell. There is also the Hindenburg, a zeppelin that went around the world in the 1930s. It was kept aloft by hydrogen. The ammonia you make has value too, though toxic; if bubbled into water, it makes ammonium hydroxide NH3 + H2O –> NH4OH. This is a common cleaning liquid. Just to remind you: you’re supposed to do these experiments outside to dissipate the toxic gases and to avoid an explosion in your house. A parent will come in handy if you get this stuff on your hand or in your eye.

Next experiment: check that iron does not dissolve in Drano, but it does in acid (that’s experiment 5; done with Muriatic acid from the hardware store). Try also copper, and solder (mostly tin, these days). Metals that dissolve well in Drano are near the right of the periodic table, like aluminum. Aluminum is nearly a non-metal, and thus can be expected to have an oxide that reacts with hydroxide. Iron and steel have oxides that are bases themselves, and thus don’t react with lye. This is important as otherwise Drano would destroy your iron drain, not only the hair in it. It’s somewhat hard on copper though, so beware if you’ve a copper drain.

Thought problem: based on the formulas above figure out the right mix of aluminum, NaOH, water and Ammonium nitrate. Answer: note that, for every two atoms of aluminum you dissolve, you’ll need three molecules of water (for the three O atoms), plus at least two molecules of ammonium nitrate (to provide the two NH2 (amine) groups above. You’ll also want at least 2 molecules of NaOH to have enough Na to react with the nitrate groups of the ammonium nitrate. As a first guess, assume that all atoms are the same size. A better way to do this involves molecular weights (formula weights), read a chemistry book, or look on the internet.

Four more experiments can be seen here. This post was getting to be over-long.As with this experiment, wear gloves and eye protection; don’t drink the chemicals, and if you get any chemicals on you, wash them off quick.

Here are a few more experiments in electrochemistry and biology, perhaps I’ll add more. In the meantime, if you or your child are interested in science, I’d suggest you read science books by Mr Wizard, or Isaac Asimov, and that you learn math. Another thought, take out a high school chemistry text-book at the library — preferably an old one with experiments..

Robert Buxbaum, December 29, 2013. If you are interested in weather flow, by the way, here is a bit on why tornadoes and hurricanes lift stuff up, and on how/ why they form. 

Metals and nonmetals

Hydrogen is both a metal an a non-metal. It says so on the specially produced coffee cups produced by my company (and sold by my company) but not on any other periodic table i’ve seen. That’s a shame for at least two reason. First, on a physiochemical level, while hydrogen is a metal in the sense that it combines with non-metals like chlorine and oxygen to form HCl and H2O, it’s not a metal in how it looks (not very shiny, malleable, etc.). Hydrogen acts like a chemical non-metal in the sense that it reacts with most metals to form metal hydrides like NaH CaH2 and YH3 (my company sells metal hydride getters, and metal membranes that use this property), and it also looks like a non-metal; it’s a gas like non-metallic chlorine, fluorine, and oxygen.

REB Research, Periodic table coffee cup

REB Research, Periodic table coffee cup

Most middle schoolers and high schoolers learn to differentiate metals and nonmetals by where they sit on the periodic tables they are given, and by general appearance and feel, that is by entirely non-scientific methods. Most of the elements on the left side of their periodic tables are shiny and conduct electricity reasonably well, so students come to believe that these are fundamental properties of metals without noting that boron and iodine (on the right side) are both shiny and conduct electricity, while hydrogen (presumably the first metal) does not. Students note that many metals are ductile without being told that calcium and chromium are brittle, while boron and tin (non-metals) are ductile. And what’s with the jagged dividing line: some borderline cases, like aluminum, look awfully metallic by normal standards.

The actual distinction, and the basis for the line, has nothing to do with the descriptions taught in middle school, but everything to do with water. When an element is oxidized to its most common oxide and dissolved in water the solution will be either acidic or basic. This is the basis of the key distinction: we call something a metal if the metal oxide solution is basic. We call something a non-metal if the oxide solution is an acid. To make sulfuric acid or nitric acid: you dissolve the oxides of sulfur or nitrogen respectively, in water. That’s why nitrogen and sulfur are nonmetals. Similarly, since you make boric acid by dissolving boron oxide in water boron is a non-metal. Calcium is a metal because calcium oxide is lime, a strong base. Aluminum and antimony are near borderline cases, because their oxides are nearly neutral.

And now we return to hydrogen and my cup. hydrogen is the only element listed as both a metal and a non-metal because hydrogen oxide is water. It is entirely neutral. When water dissolves in water the pH is 7; by definition, hydrogen is the only real borderline case. It is not generally shown that way, but it is shown as a metal and a non metal is on a cup produced by my company.