Practical investigations
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Hi, I'm doing the wine investigation. Is it neccessary for the colour of the ethanol and potassium dichromate solution to change from orange to green before I can measure the absorbance in the colorimeter, can't I just take the measurement while it's still orange? It takes ages to change colour.
Igloo
You must be patient and wait until the dichromate reaction is finished, otherwise the contents of your mixture will be constantly changing giving you conflicting and unreliable readings. I know that the reaction is slow, but you could set up several different mixtures whilst you are waiting, and then carry out all the colorimeter experiments later in one go.
Always carry out a risk assessment and check with your teacher before starting any practical work.
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: 13 February 2006
