Which has a higher internal energy - a 'nearly boiling' hot cup of coffee or an iceberg? This is the ‘q vs T paradox’. The mass of the iceberg is greater so it has a higher internal energy despite being colder. Ask students to explain what happens when you place the cup of coffee onto the surface of the iceberg – why doesn’t heat flow from the iceberg to the coffee to make it boil? The discussion of why heat dissipates from hot to cold is useful in reinforcing the role of entropy.
An easy macroscopic lecture demonstration of the effect of temperature on the rate is to take three glow sticks and three beakers into the lecture. Place beakers side by side. Place room temperature water in one beaker, ice water in the second and very hot water in the third. Place a glow stick in each beaker and ask students to predict what the difference will be. Leave equilibrating while you do something else, then come back and turn off the room lights. Discuss in terms of collisions and chemiluminescence.
To emphasise the quantitative aspect of the first order decay process, you can use a demonstration on the visualizer – take 40 M&Ms and place them face up (the ‘M’ up) in a clear Tupperware container. This is the population at t=0. Ask a student volunteer to come and shake the container (gently) for 3 seconds and remove the M&Ms that are now face down – the remaining population is recorded as t1/2 on a graph.
The ChemBytes website has a sophisticated set of learning resources for chemical equilibrium. Simulations and practice problems are integrated to help students understand the basics.
The ChemBytes website has a sophisticated set of learning objects to help students understand specific fundamental topics such as aqueous solutions. Dissolution and speciation are covered in detail with simulations and visualisations.
I think what I try to get students to see is that we use models and you use a model, while it works. Then when it doesn’t work you develop a more sophisticated model, and what we’re doing now is developing a more sophisticated model of the structure of the atom, of bonding between atoms. So they find that difficult, the fact that you’re putting aside the model you used previously and developing a more sophisticated one. I think that’s something, it just knocks their confidence a bit.
