Practical investigations
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Hi I am doing my individual investigation on vinegar analysis, and I am really confused. How did activated charcoal decolourized vinegar?
Igloo says
Most students use activated charcoal for decolourising solutions without ever asking why this actually works, so it’s good that you are inquisitive about what is going on.
Charcoal is obtained by burning organic material – wood, for example - in a limited supply of air. It is converted into the “activated” form by heating it with steam to about 1000 °C in the absence of air.
This treatment produces a very porous solid which has an extremely high surface area. This property helps to make it an ideal medium for the adsorption and absorption of organic chemicals. Adsorption means that the chemical has an interaction with the surface of the material whereas absorption implies that there has been an incorporation into a host structure through pores in the surface.
Activated charcoal can remove specified substances from mixtures of gases or solutions. The amount of material removed depends on the capacity of the activated charcoal as well as the affinity of the material for the charcoal.
As you have discovered, chemists often use activated charcoal to remove coloured impurities from solutions. In general, coloured substances, such as those in vinegar, tend to have molecular structures that make them bind preferentially to the charcoal, so this is why they are removed from solution when the vinegar is stirred with it.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 24 January 2006
