[luvana]

Hi, I am doing a design experiment on homologous series. My idea is to measure the time it takes for different alcohols from the same homologous series to react with H3PO4 (to completion).

My question is how do I measure it? How can I know when the reaction has gone to completion? What apparatus do I use?

Also, is this an okay experiment in overall? For something that I might be graded on, should I choose another design?

Thank you! =)

[orgopete]

My question is how do I measure it? How can I know when the reaction has gone to completion? What apparatus do I use?

I think this is the purpose of planning the experiment. Changing the alcohols is the easy part. What is the reaction you are proposing? Indeed, how do you know it has gone to completion? Chemists do have a number of tools available. Picking one will depend on what one is measuring.

[luvana]

I think this is the purpose of planning the experiment. Changing the alcohols is the easy part. What is the reaction you are proposing? Indeed, how do you know it has gone to completion? Chemists do have a number of tools available. Picking one will depend on what one is measuring.

Thank you for your reply. Obviously, by reacting an alcohol with H3PO4 leads to dehydration. We end up creating an alkene, while releasing water and proton.

The problem is that I have no idea what I can possibly measure in this reaction. Is it even possible? Any ideas?

By the way, I was thinking about another experiment. Instead of reacting with H3PO4, I could react the different alcohols (i.e. methanol, ethanol, propanol etc.) with solid sodium, and take the time of completion. Does anyone know how big of a difference the reactions would give (in time)?

[Arkcon]

Again, regardless of the reaction you chose, what are you capable of measuring?  Can you measure the reactant being used?  Can you measure the product?  Does the reaction produce or consume heat, so that you can track it with temperature?  How do you know about "the proton" , can you measure some property of "it".

[Babcock_Hall]

Have you thought about monitoring the reaction with TLC?

[curiouscat]

Wondering if you could choose an alcohol such that the resulting alkene is a gas. Then allow gas to escape & monitor via weight alone.

I'm assuming alkene won't dissolve substantially in the alcohol?

Could you add something like Br-water & monitoring colorimetrically?

Not sure, just brainstorming.