Recent Posts by David Allen

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 ...

Hot off the Press

A couple of recent articles in the science section of the BBC have caught my eye lately. The first one I read a few days ago or so ago concerned the atmosphere of Mars. It turns out that over time, most of the Martian atmosphere has been lost into space (how, I’m not too sure) but what caught my eye was the method used to determine the rate of loss of gas in the atmosphere to space. I have written about a ...

It’s that time of year

So here we are, April is with us and in the UK Spring is most definitely here. Which means one thing if you are in the second year of the IB diploma … exams. This year, the exams in chemistry start on the afternoon of Thursday 11th May (paper 1 and 2) followed by the morning of Friday 12th May for paper 3. Which, depending on when you read this, gives you around four weeks until the examination. So, how is your ...

VX – What is it?

Over this last month or so, the nerve agent VX has hit the headlines for all the wrong reasons but I did think it was worth looking at the chemistry of this molecule in this moths blog post. The obvious question is what is it? VX, or, to use the full IUPAC name is actually Ethyl ({2-ethyl}sulfanyl)(methyl)phosphinate. It is referred to as VX as it is a ‘V’ series of nerve agents (‘V’ stands for venom) and was first syntheiszed in the ...

Man Made Minerals

This blog post was inspired by a recent BBC article I read on minerals. The full article can be found here if you would like to read more (after you have read this blog post, of course!): http://www.bbc.co.uk/news/science-environment-39133897 It has recently been announced that over 200 ‘new’ minerals (4% of the total known minerals) have been discovered – these minerals own their existence to us. As strange as it sounds, human behaviour has led to the formation of these substances. To me, ...