Experiment 12: Copper Sulfate and Iron

This chemical reaction is very interesting.  If one dissolves copper sulfate in water and places a bare iron nail in that, the iron replaces the copper in the sulfate salt and makes very fascinating hairy growths on the nail.  I did this reaction with some of my copper sulfate, commonly available as root killer for sewers, and it turned out quite well.  I like how the solution turns a greenish color and the nail becomes a furry, coppery tree trunk.  Check out my YouTube time lapse I made of the reaction!

Raspberry Pi CPU Temperature

After finding some free time recently, I decided to come back to my Raspberry Pi, so I whipped up a quick website.  I currently have the Apache server with PHP running on my Model B Pi.  I like webpages that have a link to something in the real world, so I made a page that shows the temperature of the Raspberry Pi CPU.  You can view the HTML, CSS, and PHP code right here.  The HTML code is pretty basic; just the regular tags for the simplest of webpages.  One interesting tag, though, is the <meta> tag, which tells the viewer's browser to automagically refresh the page every 10 seconds to display the most up-to-date CPU temperature information.  All that the CSS does is give the PHP-generated text some snazz, centering it, making it larger, and coloring it.  The CSS also gives the page a nice repeating background image (located on the Raspberry Pi in the same directory as the webpage), available here.  The PHP code is the really interesting part.  It may be intimidating; I condensed it so save space.  However, it really isn't all that complicated.  The first line executes the command "cat /sys/class/thermal/thermal_zone0/temp" and assigns its output to the variable "$outarray".  The command just reads the Raspberry Pi CPU temperature file, located at "/sys/class/thermal/thermal_zone0/temp".  This file contains the Raspberry Pi's CPU temperature in millidegrees Celsius.  "$outarray" is apparently an array, so the next line treats it as such, reading the zeroeth element, dividing that by 1,000 to get degrees Celsius, and then multiplying it by 9/5 and adding 32 to get Fahrenheit.  It then assigns this temperature to the variable "$temperature".  The last line of the PHP code echos (prints on the webpage) this result, using the "round()" command to get rid of unnecessary decimal places.  Directly after this block of PHP code is "&deg;F", which codes for the degrees symbol and then an "F" to represent Fahrenheit.  Thus, the end result might be "101.3°F".  I am quite pleased with the results- I have a nicely-formatted auto-updating webpage that shows my Raspberry Pi's CPU temperature in Fahrenheit.  Have a blast, and don't bake your Raspberry Pi!

Experiment 11: Ultra-Dangerous Mossy Lead/Tin Alloy

I had some 60/40 tin/lead solder that I decided to experiment on, so I first melted it into a nice blob.  Pretty, hefty, and solid, but not super-exciting.  So, I decided to try pouring the molten alloy into water, to see what would happen and to hopefully make nice granular pellets for science experiments.  For those of you who don't know, "mossy" metal is what you get when you pour metal into water, so it makes really shiny oddly-shaped blobs.  I poured a coffee bean can full of water and then melted my solder in a tin can with a propane torch.  It melts quite easily.  Then, I poured it into the water, trying to pour slowly and make the solder fall in little blobs.  It worked pretty well:

As you can see, I got some really shiny mossy solder.  I also got three weird "fuzzy" spheres of alloy, which brings me to an extremely important point: this is dangerous.  I hypothesize that the fuzzy spheres are caused by a fairly large amount of molten (read: hot) tin/lead alloy exploding itself inside out while under water, kind of like popcorn.  They are really quite thoroughly exploded.  If this molten tin/lead mixture exploded onto your skin, eyes, or other important body parts, I can predict that you would not be happy.  I was wearing splash goggles and full winter clothing, but leather gloves and a face shield would have been even better.  Have fun, and be safe!

Experiment 10: Silver Pennies by Electrochemistry

So I saw some little kid on YouTube trying to explain how to electroplate pennies with zinc, but he was probably six years old and really didn't go into detail about what to do.  I had seen the silver & gold pennies experiment with zinc sulfate, but since I didn't have zinc sulfate or the stuff to make it, I decided to wing it.  I first placed some zinc metal I smelted out of pennies into a jar of vinegar and left it overnight to dissolve into zinc acetate.  It was probably about a 1/2 cup of vinegar.  On looking back, overnight was too long and made the solution too concentrated, so maybe leave yours dissolving for 4 hours.  When doing the electrochemistry, you do not want a very concentrated solution, or else crystals will grow instead of a nice atom-thin coating.  Anyhow, after I had the zinc acetate solution, I buffed a penny with a wire buffing wheel and a Dremel tool.  This cleans off the gunk.  After that, I cleaned it with alcohol to take off grease and other minor impurities that might interfere with the electroplating process.  Next, I used the 3.3V line on my lab power supply and hooked up the penny to the negative lead and a piece of zinc metal on the positive lead.  I placed them both in the zinc acetate solution, making sure that the negative lead was submerged and the positive lead was not.  If the positive lead is in the solution (instead of just the zinc metal) it can corrode.  After rotating the penny a few times, I had a very good plating of zinc.

I noticed that the plating was not very shiny, so I buffed it with the metal brush Dremel buffing wheel.  It turned out absolutely amazing!  Here are pictures of the finished penny (the images do little justice to how nice the penny really looks).

Experiment 9: Hydrogen Balloon Explosion

I find hydrogen and oxygen interesting, especially when they combust.  In this experiment, I ignited a balloon filled with pure hydrogen gas.  To make the gas, I placed 0.6 grams of magnesium powder in a balloon and then placed the balloon on the top of an Erlenmeyer flask filled with 50 mL of 1.0 molar hydrochloric acid.  When I tipped the balloon to allow the magnesium powder to contact the acid, the reactants reacted to form magnesium chloride and hydrogen gas.  Since the reaction is exothermic, it grew quite warm.  After I tied the balloon off, I taped a candle to a yardstick and lit the candle.  If you want more gas, and thus more fun and danger (whee!), you should use more acid and more magnesium.  In this video I show the results, using my lit candle to ignite my very awesome gas:

Experiment 8: Electrolytic Rust Removal

Electrolytic rust removal is very helpful for removing rust from ferrous objects, as it does not damage the underlying metal and is quite a good "lazy" method.  I had some rusty railroad spikes (no, I did not steal them from an active railroad - October Sky), so I tried this method on them using my lab power supply from Experiment 7: ATX Computer Power Supply Conversion.  To actually remove the rust from the spikes, I poured one gallon of water and one tablespoon of washing soda (not baking soda or baking powder) into a bucket and stirred.  For my anode, which connected to the +12V terminal and is eventually eroded away, I used a flattened out wall of a steel soup can.  The cathode, which the rust is removed from, was obviously my railroad spike.  After I connected the +12V and GROUND terminals, I made sure that the leads got good connections to the electrodes by testing for a voltage drop with my voltmeter.  The voltage should drop if the electrolysis is actually running.  Every so often I turned the spike around to ensure that the anode had a good "line of sight" to all the surfaces.  Note that while it is fine for the black GROUND wire to be submerged, you will destroy your positive lead if you submerge it.  Once I saw that all the corrosion on the spike had turned black, I took it out of the bucket and scrubbed it off with a bristle brush.  After that, I washed it with hot water to warm the piece, and after drying it with towel, let the stored heat dry off the residual water.  I got some very nice results, so here are the before and after pictures:

Experiment 7: ATX Computer Power Supply Conversion

As I said before, I purchased an ATX power supply unit for Experiment 1: Hard Drive Sander.  I have been in need of a good lab power supply for multiple experiments, so I decided to modify that computer power supply to make it into a lab power supply.  First, I unscrewed the case and unplugged the fan connector from the PCB inside to give better access to all the wires.  Then, I chopped off all the computer connectors at the ends of the wires and grouped the wires all together by color.  I drilled some holes for binding posts in the side of the PSU and two more holes for LEDs.  After I installed the binding posts, I soldered all the black (ground) wires to one post, all the orange (3.3V) wires to another, all the red (5V) wires to another, and all the yellow (12V) wires to yet another binding post.  Having done so, I connected the green wire, which normally goes to the front switch on a computer, to the ground so that the power supply would power on when I flipped the switch at the back.  The green wire must be connected to the black to turn on the PSU.  Also, the brown 3.3V sense wire must be connected to the orange 3.3V terminal.  My supply had a blue -12V wire and a white -5V wire, but the binding posts I used were ridiculously expensive, so I opted to not connect those wires to binding posts and ended up leaving them inside the supply.  I hooked up the purple (+5VSB) wire to an LED and then to ground using a 330 Ohm resistor in the middle.  The purple wire outputs +5V if the power supply is switched on and connected to an outlet.  My last connection was the grey (POWER_OK) wire to an LED and ground with another 330 Ohm resistor.  The POWER_OK signal is low, or off, if the supply begins to give bad voltages.  That way computer processors can turn off before they are damaged by incorrect voltages.  I basically used the +5VSB and POWER_OK LEDs to show me if the supply was connected and on, and if it was supplying the correct voltages.  To finish everything off, I plugged in the fan connector again and the screwed the supply's lid back on, this time leaving the fan on top of the case because there was no space inside.  I measured the voltages and everything was correct and stable to +/- 0.01V, so the modification passed! I later added nice labels.  Here is the finished lab power supply:

Update to Experiment 1: Hard Drive Sander

As I said in a previous post, I ripped apart an old hard drive and made it into a disk sander.  My power supply for that sander finally arrived!  I tried plugging the sander in and then plugging the PSU into the wall while its switch was on, but nothing happened.  After some frantic hair-pulling trying to figure out if the supply was dead, I found a solution on the Internet.  PSUs need a signal from the motherboard to actually turn on, even if they are plugged in, so jumping the green wire to a black wire on the motherboard connector fakes that signal.  I tried this, and amazingly, the HDD spun up and became a high-speed sander!   I was able to nicely sharpen a railroad spike into a chisel for chopping stuff.  I also sharpened a wooden dowel into a conical point and gave a regular pencil an unnaturally sharp point.  I noticed that after 2 minutes, the HDD spontaneously shut down.  The PSU's fan still was spinning, but the HDD consistently shut down.  However, I can cycle the supply by flipping the switch on and then off to fix the problem.  I believe that the HDD figures out that there are no signals from the motherboard and then decides to shut off.

Experiment 6: Hot Ice

In traversing the wide Information Superhighway, I found NurdRage's very neat hot ice video.  I used his homemade method and used 1 liter of clear vineagar to 3 tablespoons of baking soda.  His method worked very well.  When I boiled it down, I did not notice a floating crust but rather a quick-forming rim of crystal around the pot.  Once I saw that (it took a while), I immediately took the sodium acetate trihydrate (the end result) off the stove and cooled it in the refrigerator.  When I stuck my finger in to see if it was cold, it froze!  I was happy that I had made it work on the first try.  After I microwaved it for 30 seconds and cooled it again, I placed a crystal of the sodium acetate trihydrate in and it froze very nicely and beautifully.  My solution actually turned out to be quite clear.  The experiment gave a warm feeling of satisfaction and was also quite warm physically, due to the exothermic freezing reaction.

Experiment 5: 9V Battery Clips

Cool little thing I discovered - by peeling the casing back on a 9V battery, one can salvage a clip for connecting other 9V batteries to circuits - sort of like battery clips commercially available.  I did this by carefully twisting and rolling the metal case away to reveal the six small batteries inside the larger 9 volt.  The little terminal tab at the top popped out, and I was able to solder wires on to the backside, like so:

As you can see, it is just the top of a dismantled 9V battery with wires soldered to the back, but it works quite well for attaching power to circuits.