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Jule

Design Lab - Variables?

Hi everyone,

I am having trouble defining the variables for my design lab.

My idea was to oxidize and unknown alcohol and then use the IR spectrum to determine the identity of the ketone and therefore the alcohol.

I'm not changing any temperatures or concentrations so I'm not sure how to define the variables. Could anyone help me?

Thanks :)

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Your experiment needs to be something you can graph, and you must have an independent variable that you can change and a dependent variable that you can measure. If you don't have these things you will get a very bad score. So I'd advise that you change your experiment a bit. Make your research question something along the lines of 'How does X affect Y?' with X being the independent variable and Y being the dependent variable.

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Your dependent variable would be the 'unknown alcohol'. lol. So essentially, it can't be unknown! You have to choose different alcohols e.g. methanol, ethanol etc. So you can do something like the type of alcohol used as your dependent variable

Independent variable would be um i'm not too sure actually D: What you're using to oxidise the alcohol? like the sodium/potassium dichromate solution used for example.

Then you need to mention your controlled variables. e.g. the temperature, the concentration of the sodium dichromate solution, the volume of alcohol you will oxidise etc. You also need to give an explanation for how you will be controlling your variables. e.g. the temperature of 30 degrees will be controlled through using a water bath at 30 degrees.

Make sure that the stuff you have included in your controlled variables is mentioned in your method. :)

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Maybe you could, as Ayumi said, use different alcohols and have number of carbon atoms in the longest carbon chain your independent variable (e.g Methanol = 1, Ethanol = 2) and then have the dependent variable as something to do with the IR spectrum (wavelength, frequency etc.) and see if there is a trend.

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Maybe you could, as Ayumi said, use different alcohols and have number of carbon atoms in the longest carbon chain your independent variable (e.g Methanol = 1, Ethanol = 2) and then have the dependent variable as something to do with the IR spectrum (wavelength, frequency etc.) and see if there is a trend.

So do you mean something along the lines of "How does the number of carbon atoms in the longest chain affect the wavelength?" Or would it make more sense to look at the affect of double bonds and branches off the carbon chain on the wavelength?

Thanks:)

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Sorry, I'm not sure because I only did SL. Do you know, based on the theory you've done, what affects the wavelength more out of the longest carbon chain, number of double bonds, branches etc? If so, use that variable. But I think you're on the right track for a good research question :)

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