Showing posts with label Moment. Show all posts
Showing posts with label Moment. Show all posts

Wednesday, July 3, 2013

Moment of Science: Whoosh Bottle

Here's a simple experiment on a large scale.  Take an empty 5-gallon water jug.  Coat the inside with ethanol.  Pour out excess.  Light a match on a stick.  Hold flame over the mouth of the jug.  WHOOOOOSH!

This is a great experiment for Combustion Reactions.  Coating the inside of the jar with ethanol removes the oxygen from the system.  Without oxygen, you can't light the fumes.  Except for the fumes escaping from the mouth of the bottle.  The oxygen and ethanol combust as the oxygen is sucked into the bottle creating the Whoosh sound.

I made sure to repeat this experiment on the day of the Reactions Test for my chemistry class.  The particular combustion reaction was the final question on the test.  Something like:

____ C2H5OH + _____ O2 -->  _______________________________

Wednesday, June 26, 2013

Science if Awesome (GIF)

Speaking of Goldenrod Paper.  I forgot that I had tried to make a GIF of the process.  We were doing something in class for them to make animations, and I wanted to try a GIF maker on my iPhone.  As you can tell, this particular message has be read so many times that the words kind of show up at the beginning.  When you first do it, no one can see it - especially from across the room.

I need a little bit more practice with my GIF making, but I think it is a good start!

Moment of Science: Goldenrod Paper

The best thing about teaching high school chemistry is the incredible stockpile of chemicals.  Many are harmless, but some can be incredibly dangerous.  Only one of those categories will grab be attention of the students.  Partly from boredom, but mostly to interest the kids, I began doing weekly "Moments of Science" every Wednesday.  At the beginning of class, I would set up some crazy demonstration.  Most of the time, I could work the demonstration into our unit.  Other times, it was just to show something that I found cool.  The kids really loved it and would remind me whenever Wednesday came around.

I had a good time with them as well.  I don't have any pictures or videos of me doing them.  I wish I did.  But I can always find them on the You-Tube.  Here I will tell you how to do it.  Some of them (the more dangerous ones) you could only really do at a school, but some you can easily do with homemade materials.  I hope you enjoy them.

I begin with demonstration I did on the first day of school every year: Golden Rod Paper.  Goldenrod paper contains a certain dye that acts as a base indicator.  Ammonia causes the yellow paper to turn "blood" red.  I begin by talking about blood donations, needles and the need for blood to help people as I put my hand in an unknown fluid.  As my hand is in the liquid, I say my pores are opening and blood vessles are dilating and that my hand is tingling.  Then I suddenly slap the yellow paper leaving a blood stain the shape of my hand.  Most of the kids freak out believing it to really be my blood.

The ones who don't believe it, think that it is just water.  So I put some water on a Q-tip and nothing happens.  Eventually I tell them that it is ammonia and how bases can change the colors of things called indicators.  Water, which is neutral, doesn't change the color.  I also ask them what would happen if I put an acid on the paper like vinegar.  It will go back to yellow.

You can also write hidden messages in wax or tape which are revealed by a spray bottle of Ammonia.  I found a golden rod crayon and wrote "Science is Awesome" then sprayed it with the ammonia.  The best part is the evaporation of ammonia which leaves allows the paper to return to its original color.  There are a lot of science topics that you can talk about this just this one demonstration.  It's safe, fairly clean, and you can do it at home if you find the right materials.  Enjoy!