Top Tips for Success (3)

Read the question - it may seem like an obvious thing to say but make sure you do this. Think! What is the question asking me. A question that English speakers (if you are taking your exam in English) seem to get wrong is along the lines of: Cl2 + 2Br- --> 2Cl- + Br2 What is the oxidising agent? English speakers see the word 'oxidising' and immediately think oxidation. The substance being oxidised is Br- and they write this as their answer - but ...

Oxidation States of Vanadium

Here is a great lab to use, whether it with regards to redox (topic 9) or transition metals (topic 13): Vanadium It deals with looking at the oxidation states of vanadium by reducing it with Zinc and the re-oxidising it with MnO4-. There is lots of good teaching to get over in this lab, from understanding redox and writing half equations to seeing that transition metals can have variable oxidation states through the colour of their ions. Please note, as with any lab outlined ...

Happy New Year

Happy New Year to everyone - wherever you are! I hope that it was an enjoyable rest for you. Here in the UK Christmas really does feel over and done with. School has started and the holiday seems a long way away. Last night we took down our Christmas tree and realised that we still had a large number of uneaten candy canes. This posed me with a dilemma..... .... give the children even more sugary sweet substances (as if they haven't ...

Sulfur Week

This week I thought I would focus on sulfur and its smelly compounds. However, todays posting will focus on an introduction to the element. Sulfur, S, atomic number 16 is found in group 6 of the periodic table. In its elemental state, it forms S8 and is yellow in colour. In nature, it is found in its elemental forms (it is mined from around volcanoes) and as sulfites and sulfates (sulfates also have oxygen present). It can act as an oxidising or a ...

Molecular pistons and redox

A redox reaction has been used to move a molecular piston back and forth. It is hoped that this will allow nanomachines to make use of it. The piston works with a man made molecule called a rotaxne. The rotaxne is a liner molecule with a napthalene complex at one end and sulfur containing group at the other end. The sliding part of the piston is made of six carbon rings, joined to form a hooped shaped positively charged ion. By ...

Ageing Wine

  We have all heard that wine gets better with age, but why?   To start with, it doesn't really improve, it's Chemistry changes. Substances such as .... .... Tannins precipitate and oxidised alcohol (ie, carboxylic acids) combine with ethanol to form esters - which improve the wines aroma. So does it taste better? Well this will depend on other things, such as the type of grape. This posting was adapted from an article in 'Focus Magazine' on sale in June 2010 on page 77.

Making Metals

We have probably all carried out the reduction of Copper Oxide using Carbon at some time, maybe to show the reactivity series or maybe to talk about redox. I was wondering though if this could be used as a quantitative IA lab, 'Calculate the % Yield of Copper Produced From The Reduction of Copper Oxide With Carbon? (To assess DCP and CEv maybe?)   If one knows the mass of Copper Oxide, one should be able to calculate the theoretical mass of ...

Potassium dichromate Tests for Primary, Secondary and Tertiary Alcohols

Here are some ideas for some easy test tube reactions that cover redox, intermolecular forces, alcohols, ketones, aldehydes, carboxylic acids and chemical tests. We can use acidified potassium dichromate (K2Cr2O7) solution to distinguish between primary, secondary and tertiary alcohols. As with all the experiments listed on this website, specific experimental details are not given. It is your responsibility to research each method and to carry out a substantial risk analysis. Primary alcohols are oxidised to aldehydes and the carboxylic acids Secondary alcohols are oxidised ...