Rates of Reaction
Video clips and animations
- The effect of surface area on reaction rates
Not a hugely exciting video, but it covers the main points. YouTube - The effect of surface area on combustion
From the Royal Society of Chemistry. DO NOT TRY THIS AT HOME! Unless this is done under carefully controlled conditions, you could seriously injure yourself, or risk a major fire. YouTube - Effect of concentration on rate of reaction
The reaction between zinc and two different concentrations of hydrochloric acid. It isn't at all obvious from the video that different concentrations are being used, but it is stated on the web page, and is clear from the results. This comes from the Ministry of Science and Technological Development in the Republic of Serbia, but the embedded video comes from YouTube. There are stills from the video if you want to save bandwidth. - Activation energy
A neat little animation to show that it isn't enough for molecules to collide for a reaction to occur. They have to collide with sufficient energy. The energy needed to get the reaction started is called activation energy. The video includes the terms "exothermic" and "endothermic". An exothermic reaction is one which gives out heat (such as methane reacting with oxygen). An endothermic reaction is one which absorbs heat (such as oxygen reacting with nitrogen). YouTube - Activation energy in the reaction between hydrogen and chlorine
The presence of UV light provides enough energy to break the bonds between chlorine atoms to get the reaction started. The reaction is explosive and blows the bung out of the tube - that's not clear until the final shot. YouTube - Catalytic oxidation of ammonia
Oxygen bubbled through concentrated ammonia solution in the presence of a platinum wire catalyst. Don't worry about the unfamiliar reaction. It is just an explosive reaction between ammonia and oxygen on the surface of a hot platinum wire acting as a catalyst. YouTube - Catalytic decomposition of hydrogen peroxide
Addition of manganese(IV) oxide catalyst to some very concentrated hydrogen peroxide solution. The gases produced are a mixture of oxygen and steam. YouTube
Other useful or interesting sites
- Bombardier beetles
Bombardier beetles have a defence mechanism which uses an enzyme to catalyse the decomposition of hydrogen peroxide as its driving force. This page looks at this in some detail, including a video - although the next link has a better video. - Bombardier beetles from MIT
More discussion of the mechanism producing the pulsed spray. YouTube - Rates of reaction on Chemguide
You might be interested in a slightly more in-depth look at rates of reaction. This link will take you to the rates of reaction menu on Chemguide. Although it is aimed at A level, you should be able to understand most of the "Basic descriptive topics". Do, however, remember that this is beyond GCSE, and don't worry if some of it doesn't mean anything to you at this stage.
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© Jim Clark 2017
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