Friday, March 29, 2013

Metal reactivity awesomeness

So, one of the things you talk about in introductory chemistry is the activity level or reactivity of different materials. Because reactivity tends to mean fizz, flash and boom, the visuals often make for great demos. Specifically, the activity series of metals can be instructive, as you can use it to predict how different metals may react in similar reactions.

This experiment is an oversimplification, I know, but it gets idea across for younger students.

Here I react three metals -- aluminum, zinc and copper -- with the commonly available muriatic acid (hydrochloric acid). It's a cheap and easy way to visualize the reactivity of different metals, using easy to find materials. Plus, it's fun. To extend this, you can try different metals, for example an iron nail. See what you have in your home or lab. Then look at an activity series chart and the Periodic Table and draw conclusions.

Safety notes: This reaction produces noxious gas and heat. Goggles and gloves should be worn. Seriously.

Sorry for the video quality. First time with a new camera. Plus I have a sinus infection, so my voice sounds terrible.

Wednesday, March 27, 2013

Making Matters: 5 things to do with paper towel rolls

We all know that toilet paper and paper towel rolls are one of the all-time classic craft supplies in the typical classroom. Which is awesome -- I love toilet paper owls and other fun projects made from these upcycled marvels. But what about using such humble supplies for science? Here are five projects
to try at home.

Ok. One toilet paper roll owl. I can't help myself.
  1. Marble Slides -- Break out the masking tape and get ready to have some fun! Using whole and halved rolls, junior designers can attach tubes to any wall creating multi-layered slides for marbles to zig-zag towards the floor. If you want to get some motion going, try attaching rolls to foam board using brass brads or tacks!
  2. Spectroscope -- Find all the colors of the rainbow in white light. Using black construction paper, cut a circle the size of the paper towel roll opening. Cut this circle in half. Tape half of the circle to one end of the roll, being sure to tape well around the edges. Attach the other half circle to the same end, leaving a narrow slit across the center. Again, tape well at the edges. Now,with your eye at the open end, look at a CD held near a light source (an incandescent bulb just behind the bulb is great). The CD will diffract the light, breaking it into a rainbow that you can see through the slit. Wow!
  3. Kaleidoscope -- Cut you paper towel tube to 8 inches. Longer will make it tough for enough light to travel to the eye. Use black construction paper to cover one end of the tube. With a pencil, poke a hole in the paper. Use clear tape and apiece of clear cellophane or acetate (a report cover, a transparency, etc.) to create a triangular tube that will fit inside the tube. Slide it in. Cover the other side of the tube with plastic wrap, pushing it down to make a little pouch and securing it with tape or a rubber band. Add beads, sequins, gems or anything small and shiny. Cover with another piece of plastic wrap and secure in place. Now hold it to the light, look through the hole and enjoy the power of reflected light as it creates an amazing display!
  4. Telescope -- Using construction paper create a roll that can just fit inside the paper towel roll. Ideally, you'll want two double-convex plastic or glass lenses, one 150 mm and the other 300 mm. If you can't come by those, try magnifying glasses - one larger and weaker and the other smaller and more powerful. You may have to experiment with different options. Tape the smaller lens onto the construction paper tube. Tape the weaker one onto the cardboard tube. Then fit the open end of the construction paper tube into the open end of the cardboard tube. Look through the stronger lens. Move the construction paper tube in and out until the object you're looking at is focused. 
  5. Pulley Towers -- Grab some old thread spools, bamboo skewers, cotton string and toilet paper rolls to explore one of the most fun simple machines. Use the rolls to make two towers -- feel free to go big, stacking two of three rolls together. To form the base, cut slits into the bottom of the tower, spread out the "feet," then tape them to a table. Thread the spools onto the skewers and place them between the towers, poking holes into the cardboard as needed. Then it's time to play! Use the string wound in various ways through the pulleys to see how the number and placement of affects the what you can lift.
    That is one complicated pulley system!
Whew! That's a lot of fun with paper towel rolls. I'm going to take a bit of break. Come back later this week for 5 MORE fun ideas!