Experiment 13: Zinc Sulfate from Copper Sulfate

I have already made instructions for an electroplating version of the silver penny experiment (Experiment 10: Silver Pennies by Electrochemistry), but, as of now, I have not been able to perfect the transition from that to a gold penny.  A chemist friend suggested that the zinc was too thick, which seems reasonable.  Thus, I needed zinc sulfate to try the more common silver penny experiment in preparation for making a gold penny.  To make zinc sulfate, I filled a test tube half-way full with aqueous copper sulfate.  Then, I took some strips of zinc I obtained by taking apart a zinc-carbon battery (i.e. like the one from Experiment 4: Carbon Rods) and, after washing them, placed them in the test tube.  Truly, mad scientists cannot be more happy when they have an awesome test tube of a mysterious blue liquid.  After approximately half an afternoon, I came back and the solution was clear.  If you attempt this, you must wait until the solution is clear, or else the copper sulfate will not be completely reacted.  The reaction is a single replacement reaction where the zinc replaces the copper in the sulfate, making zinc sulfate and copper metal.  The zinc had some weird fuzzy growths of copper, so I filtered the entire solution to obtain some leftover zinc, copper slurry, and a crystal-clear solution of zinc sulfate.  Although I said copper multiple times, looking at my real product (a black powder), it seems as if it is not copper.  Online, someone said that the reaction produces heat, which would make cupric oxide, a black powder.  They also noted that the reaction produces some hydrogen gas, so that would explain the bubbles.  Check out the time lapse below and stay tuned for a post on making shiny silver pennies!

Web-Triggered Speech on the Raspberry PI

I enjoy interfacing reality with software, i.e. LEDs with matrix programs, so I created a webpage on my Pi server to trigger eSpeak, a text-to-speech synthesizer, whenever the webpage is loaded.  I created a basic HTML page and then added some PHP code.  One side note- you must have eSpeak installed on your Raspberry Pi, and you must have added the www-data user to the audio group using "sudo usermod -a -G audio www-data".  Reboot your Raspberry Pi after doing this.  The PHP code is parsed and run the minute the server sends the page to the client, so eSpeak speaks before content appears in the browser.  If you are wondering about the code, it is as follows:

<?php exec('espeak \'You are visiting my website.\''); ?>

It is pretty straightforward, using the PHP exec(); command to execute the "espeak" command in the Linux terminal.  One good note is that "espeak" and "exec();" only like single quotes, so you must use the escape character ("\") before espeak's single quotes to prevent "exec();" from thinking you have ended your command.  For example, without the escape, PHP would think that the command was "espeak ".  After doing all that, I had a really cool webpage that spoke with real audible words through my Raspberry Pi whenever it was loaded!