Density Demo taken up a notch

I was helping out with our summer church camp and it was a science theme. They have a demonstration at the end of each day. The demo today really took my old diet Coke/regular Coke demo up a couple of notches.

First, put in a regular Coke, then a diet Coke. Ask for predictions from the audience each time about what they expect will sink or float and why.

Try:
Pepsi and Diet Pepsi
A lemon and a lime (the lime sinks, the lemon floats)
An peeled orange and an unpeeled orange (the orange floats, the peeled orange sinks)
And for a big finale, two bowling balls - one 7 lb and the other 16 lb (borrowed from a bowling alley). The 7 lb bowling ball floats and the 16 lb one floats!

And it's all about density and how tightly packed together those particles are. High density items (like people packed together on a bus during rush hour) that are more dense than water will sink. Low density items (like people in a bus during a slow time) will float!

Acid Rain Demonstration

Burningof sulphur – acid rain demonstration (Science & Society connection)
Apparatus: gas bottle, BTB indicator, glass plate, deflagrating spoon & sulphur.
Directions:
1. Fill gas bottle with water and add a few drops of BTB (indicator turns yellow in an acid or remains blue in basic or neutral solutions).
Put ½ tsp (amount is not critical) into the spoon and heat over the Bunsen burner flame. Ask a student to turn off the light so that the violet flame can be viewed.
Lower the spoon into the gas bottle, taking care not to touch the sides (see photograph). Cover with the glass plate. The white gas (SO2 and SO3) will billow and fill the air space above the blue liquid. Douse the flame in a waiting container of water (Safety alert – toxic gas produced is, use a fume hood).
Discuss with the class about societal and environmental implications of factories burning sulphur and the products that will come out of the smokestacks, like sulphur dioxide and trioxide. During this time, these two gases will dissolve into the water to form sulphurous and sulphuric acid, changing the pH from neutral to acid.
Cover the top of the bottle completely with the glass plate and shake once. The blue coloured solution will dramatically change to yellow. This indicates that the solution is now an acid. Explain how this demonstration shows how we get acid rain and the effects of air pollution on our lakes.
Extension: In Southern Ontario, there is a buffering effect of limestone (CaO) that will react with water to form calcium hyroxide (CaO + H2O--> Ca(OH)2). Since metal hydroxides are bases, this counteracts the effect of the acid rain. Therefore, Southern Ontario is not as affected by acid rain as it could be.

Silver flakes make for a cool demo

This is an oldie but a goodie. This is a demonstration that I never get tired of.

Single Displacement Reactions
Demonstration: Reaction of copper with silver nitrate.
Apparatus: coil of copper wire, large test tube, silver nitrate solution (concentration is not crucial).
Directions:
1. Place copper wire into test tube of silver nitrate. Allow students to review the activity series and predict the products of the following reaction:
Cu + AgNO3 --> Ag + Cu(NO3)2
2. Observe the reaction (see photograph). Large, beautiful flakes of silver come out of solution and the clear, colourless silver nitrate is replaced by a blue solution of copper nitrate. This colour change is evidence that the copper has gone into the solution.

Chem4kids Website - Wow!

Wow! I came across an excellent website for kids called http://www.chem4kids.com/. It should not be called chem4 kids since there is a biology, astronomy and earth science sections, too!

I don't what the target audience is, but it's a great overview of things for high school students. It has colour pictures to add interest. Done by Rader Studios, they have done justice to the topic, doing a great overview and making sure to have real life examples

The Joys of Sidewalk Chalk

I took my Chemistry 12 students out into the parking lot with a bucket of sidewalk chalk last semester. We had been talking about s, p, d and f orbitals and I love doing role play. I do a lot of role play in Biology. We chose a small element and went through the energy diagram for it, placing electrons (running students) in one at a time. It was interesting the questions that came up or occurred to me while we were doing this. You could see more clearly that some of the orbitals would overlap and were of a similar energy. One could also see that it is interesting to "look" at the atom at such a minute level and "zoom" in, so to speak.

I found that some students found it quite helpful and some found it confusing or really unhelpful. That was worth thinking about because it told me something about what kind of learners that they were.

A number of colleagues asked me about it because they saw me heading out into the parking lot with a bucket of chalk and my grade 12s. Also, I was able to ask for clarification from another fellow teacher as we moved through it.

It was definitely worthwhile to break out of the classroom and I will be searching for more small ways to do so.