The Biochemistry Option

Proteins Proteins are a group of biomolecules (or biopolymers) that form enzymes and muscles in the body. They are the chief nitrogenous compounds found in living organisms but are still only approximately 15% nitrogen. The other elements they are comprised of is carbon, oxygen, hydrogen and a relatively small amount of sulphur. Proteins are made of amino acids which, as the name implies, are made from amino groups (NH2) and carboxylic acid groups (COOH). These groups are joined together via a carbon ...

Formaldehyde

Formaldehyde was recently in the news … But more of this later. To start with, you may be asking, what is formaldehyde? Formaldehyde is the non-UPAC name for methanal, CH2O, the simplest of all aldehydes. At room temperature, it is found as a gas (boiling point -19oC). It does have a dipole moment but due to its low Mr (and hence weak London dispersion forces), it has a low boiling point. It is found in the atmosphere and also in space. Due to ...

Ethanedioic Acid Titrations

It's that time of year where if you are in IB1 you may well be starting to think about your IA. What will you do?! I hope today's post gives you some ideas. Have you thought about working with Ethanedioic acid (HOOCCOOH) or oxalic acid to give you its more common name? Ethanedioic acid occurs as a free acid in beetroot leaves and rhubarb. Could you extract it and see how much you have? You could titrate it with a base, such ...

SN1 vs SN2

I have not long been back from Oxford in the UK where I was running a revision course for OSC. One of the concepts that the students seemed needing clarifying was when to decide when an organic reaction was SN1 or SN2 so I thought it may be worth sharing this with you in this blog post: First of all, some definitions. S = Substitution (there are other types of mechanisms out there such as elimination and addition.) N = Nucleophilic (it is ...

Redox Cells: Revision Checklist

When I teach about redox cells, I like starting with the Daniell cell. It is an example of the world’s first battery (cell) and if you remember the details of it, you can apply to same rules to any unfamiliar redox cells. First, a diagram of the cell itself: Hazmat2, via Wikimedia Commons (CC BY 3.0) Note that the zinc half cell is on the left and the copper half-cell on the right. This is important to remember when it comes to ...

Global Warming

Global warming is still a topic that stirs a range of emotions in people. Is it real? Is it made up? Is it something to worry about or not? Will it actually affect you? But, love it or hate it, the topic is not going to go away. We have just had some training on how to teach this and I thought it was worth sharing with you. Take the premise 'Global Warming is going to cause more extreme weather patterns'. Then, think of the ...

Acid Deposition

The topic of acid deposition can be found in the SL section of the acids and bases unit, section 8.5. As a teacher, when I first read this title I had no idea what it meant, but, as with most things in the IB, the title is actually quite descriptive, once you know what the title means. The key word is ‘deposition’. It means (according to the definition in the online dictionary by Merriam-Webster), simply, ‘the act of being deposited’.1 So acid deposition ...

Superacids

The concept of superacids was a new on to me until the other day when I read about a chemistry competition that had been held in Moscow earlier this summer. You may have been in this very competition so, if you had, and I get something wrong, please do put me right! The competition asked students to 'design' (on paper) an alien blood that resembled the blood in the 'Alien' movies. If you recall, this blood needed to be capable of ...

An Introduction to Equilibria

Equilibria can be a tricky concept to understand. In order to understand it, you need a good idea of reversible reactions and then a good idea of a dynamic equilibria. So, what is a reversible reaction? Put simply, it is a reaction in which products can be turned into reactants, but reactants can also be turned back into products. This can be shown using the ⇌ symbol: Reactants ⇌ Products For example, ammonium chloride will thermally decompose into ammonia and hydrogen chloride gases, but these gases will ...

Collision theory and mechanisms – linking it together

I’ve just started teaching the kinetics topic to my students and so far we have focussed on the collision theory. Have you heard of this? The collision theory explains to us what happens during chemical reactions in terms of the collision of particles. In order for a chemical reaction to occur, particles need to come together (collide) with sufficient energy (speed). This is called the activation energy (and is defined as the minimum amount of energy required for a chemical reaction). If ...