Use red flags on lecture slides every time a 'new' defined word is used, to reiterate the meaning which is different to the meaning they might have encountered before. Even the word ‘equilibrium’ which has a meaning in the chemistry context and an everyday meaning. There will be literally a red flag on the slide.
Le Chatelier’s principle is quite cumbersome in its wording, so break that down into language that’s easier for students to understand - that’s called repackaging. Repackage of the concept and wording into language which students understand and can relate to. For example, if you heat the system up, both reactions get faster. One gets faster and faster and the other one gets faster and faster. That is good terminology that the students will understand.
It’s really important always to keep going back to links of where they might have seen equilibrium previously, because then they start to get the idea of chemistry topics being interrelated. Even put at the end of each lecture a little problem, for example, ‘how is equilibrium related to acids and bases?’ Even if they don’t understand it yet, just mention it so it’s in the back of their mind when they do learn about that topic.
Use several real life examples with different ways of causing the equilibrium to shift. Swimming pool chemistry:
HOCl can enter the cells of undesirable organisms to kill them, but OCl- can’t, hence if the equilibrium is too far to the right it won’t act effectively. If you add acid (say HCl) the position of the equilibrium shifts to the left, producing more OCl-. That’s partly why the pH of the pool is important.
Always show the corresponding reduction process when discussing oxidation and vice versa. Ask students to think about where electrons are moving to or from.
Start with HA and move on to specific chemistry. Reinforce pKa and connect with buffers by asking students to pick conjugate acid/base combinations to make up buffers with different pH. Use the concept that adding strong acid to a buffer converts it to a weak acid, increasing the overall concentration of weak acid.
Use everyday examples. A great question to have at the end of your lecture would be ‘What is reduced when my bike rusts?’ They might understand that their bike rusts, but what is reduced? Oxygen and water are reduced. But we don’t see the reduction, we just see the iron changing. You have done your job well if someone asks the question ‘What is reduced when my bike is oxidised?’
Put zinc metal in copper sulphate solution and record it with the visualiser. Have it running as you talk about the push and pull of electrons. Then bring it up and say, ‘look what’s happened here, the zinc has rusted’. Students make more of a link when they see things being visualised. The oxidation of metal has a very visual impact on them. But then, they might forget about the reduction side, so you need to remind them of it.
If you put copper metal in a silver nitrate solution, the solution becomes blue and you get silver metal. Ag+ is becoming Ag and Cu is becoming Cu++. The students see both oxidation and reduction happening - and happening at the same time. If you do it close to Christmas you can use the copper filament to make a Christmas tree, and then you get a nice silver on the Christmas tree. They know that it was a colourless ion solution, but then they can see silver on the Christmas tree. So they can easily see the reduction.
