Recent Posts by David Allen

Teaching optical isomers

I've just started to teach this topic to my students. It doesn't take too long but I do find it an enjoyable topic to teach. But how do you teach it? I always warn the students that the topic is jargon heavy - the words / phrases used in the topic such as  chiral, racemic, racemate, optically active are all pretty specific to optical isomers and are not used outside of the topic. In my teaching I have found that students understand the ...

Optical isomerism

Optical isomers are hard to conceptualise. They are molecules with the same molecular formula and structural formula. They look exactly the same both on paper and in the real world. However, they only exist in pairs, it is only possible to get two optical isomers of the same molecule which makes things a bit easier to deal with (it should be notes that a molecule such as C5H12 has three isomers - not optical isomers but structural isomers, namely pentane, 2 methylbutane ...

Putting your course together

This blog post is primarily aimed at teachers new to the course …. But that said, even if you are an experienced teacher it is always worth reviewing how you do things. There are always lots of things to consider when setting up the course. Do you teach by yourself or do you share your group with another teacher? First things first I’m aiming this blog post at teachers who teach a class by themselves as in my experience, this seems to ...

Gas Volumes

I have written this blog post with all you new first year IB students in mind. If you have started the course recently (or about to start the course very soon) it is likely that the first or second topic that you study will be ‘Stoichiometric relationships’, which is just a posh way of saying ‘moles’. That said, if you are an old hand, a second year IB student don’t stop reading! This blog post contains some important revision for ...

Limiting reagents

Limiting reagents is a concept that is easy to understand in one context... but tricky to understand in another. Before I expand on this statement, what do I mean by limiting reagents? Well, unless you have some super precise mass balances, when carrying out a chemical reaction you will always add too many atoms / molecules / particles of one substance and not enough of the other. The one that you have added too much of is the reagent that is ...

The new EE – How are you getting on?

By Wednesday, August 2, 2017 , 0

The new extended essay (EE) guide has been out for a while now – how are you doing with it? Has it changed much in the way you set up and run your EE programme? From the chemistry side of things, I hope you have not seen many (if any changes). Students still need to carry out research and whilst not compulsory, will hopefully carry out some lab based research. That has all stayed the same. The research question (RQ) is also ...

Synthesis of Aspirin

Aspirin has been with us for long time - the first documented reports of its use occurred over 2000 years ago. That said, the aspirin may not be in the form that you instantly think of (ie, a tablet) but it has been used all the same. Aspirin is an analgesic, which means it has pain killing effects and it has been well documented that the ancient Egyptians used a special tea made out of willow bark to treat a number ...

Practical application of the ideal gas equation

How many moles of air are in your lab? What mass is this air? These are a couple of great questions you can set your students and ask them to come up with some answers using the ideal gas equation. You will need a barometer (to determine the air pressure), a thermometer (to determine the temperature of the lab) and a rule to calculate the volume of the lab and hopefully some imaginative students. I carried out this work with my class a while ...

Carrying out a good IA project

Have you stated your Internal Assessment(IA) yet? If you are a 'May session' school, this anytime from May of IB1 until December of IB2 seems a likely time that your school will carry this out with you and ask you to write it up. Which means that you need to get some ideas on what types of things you can investigate. However, the aim of this blog post is to give you some ideas for writing and carrying out a good ...

Good Practice – Carrying out a lab

Here is an idea I got from a colleague of mine recently for a novel way of getting your students to plan a lab investigation. It is a model that could be rolled back and used in a variety of labs and it is very straightforward to do. Essentially, you give the students a task (for example, testing for halides) and then give the students a framework in which they can plan their own personal investigation. For example, you give them ...