[josharoon]

Hi there,
I posted this in the high school forum, however with many views and no replies I'm guessing it was the wrong spot to post it.

I'm currently in senior high school and I've just been given an assessment in which I have to analyse a consumer product to gather information on how accurate the claims of the company selling the product is. The requirements of the task is that there must be two methods of analysis (titration, gravimetric, optical etc.), of which at least one must involve a chemical reaction.

I have had been recommended a few substances to analyse such as caffeine (as in pills), nicotine (in patches), nitrates (in fertilizers) etc.

However I am also wondering whether, if possible, the analysis of ethanol blend fuels is worthwhile, ie. attaining the true levels of ethanol in the petrol as opposed to its advertised percentage.
Does anyone have any ideas on how I could do this?
I was thinking of recording differences in combustion of E10 vs Petrol, adding water to E10 blend to absorb the alcohol added to the fuel etc. Although I'm sure there are better ways of doing this...

Also on the other hand if any of this seems not possible to execute in a high school lab, are there any suggestions of other pracs to do with consumer product analysis?
Thanks,
Josharoon

[ATMyller]

E10 undergoes phase separation with water, which is normally a problem, but could be used in proposed research. Around 0.5% (volume) of water in the E10 mixture and you'll get two phases one heavy with most of the alcohol and water in it and lighter one with the hydrocarbons.

Other possible, but harder options would be fractional distillation and reaction with sodium. Sodium turns ethanol into sodium ethoxide (CH3-CH2-O-Na) which can be gravimetrically measured after the hydrocarbons are either distilled or evaporated away. Problem with this is that reaction releases some heat so you have a fire hazard and if there is water in the fuel mixture a very serious fire hazard.

Spectrophotometry and gas chromatography could be easy and fast analysis methods, but I don't think high schools usually have such equipment.

[DemonicAcid]

Unless you have a vacuum distillation setup where you could bubble N2 through the mixture I would not recommend using sodium due to the hydrogen gas that would be released and the high risk of fire/explosion. Fractional distillation should definitely be one of your choices. Since gasoline and ethanol have significantly different heats of combustion, bomb calorimetry might be a viable option