[Confusionist]

Hello! First post on the forums!!

Anyway, I'm a high schooler right now finishing my last semester! I recently transferred to a very fancy (and rich!) high school. Around 3 weeks ago, the professor for my Biomedical Sciences class told me that me, being an A student from my other schools who took rigorous courses, was able to use ANY AND ALL lab equipment. He said I could use the lab for around 3-4 hours per day and he would provide whatever I needed! He added that this could lead to some pretty snazzy recommendations from him in the future if I present him with a nice research paper.

But I have no idea what to do! So, I'm coming to all of you for ideas. I would have put this in the high school category, however high school level experiments are not what I'm looking for at all. Now, this is a college level course. In this course, we go through the entire process of investigating a murder with all the fancy tools. I would list everything we have, but that would take hours. I realize I'm leaving this pretty broad, but honestly I don't have too many ideas. Earlier this year I experienced seeing a match lit in a school environment for the first time. I don't have too many experiment ideas partially because every other school I've attended has had crazy safety regulations set up that, quite frankly, completely screwed over a lot of my hands-on learning experience.

And before anyone asks, I did ask my professor what his thoughts are on what I should do. He said "use your imagination". 

Thanks!

And I probably forgot to mention quite a few things in here so please tell me if anything is unclear. 

Edit: Took a closer glance at other forum posts, I'm not quite as advanced as all of you, aha. But I think the lack of complexity of my post gave that away. 

[Enthalpy]

Hi Confusionist, welcome here!

You expect suggestions for chemistry I guess, since you post here?
Maybe you could try this polymer:
http://www.chemicalforums.com/index.php?topic=62053.0
and tell us (tell me!) what is obtained? Already the atomic composition would be a step forward, the density as well.

I obtained it very easily and without expecting it, quickly at room temperature and pressure. It may have been a soft polyolefine of low density, but could have contained oxygen as well.

Please be careful if using sodium hydroxide: protective goggles and so on. Well, your teacher will tell you.

[Enthalpy]

If you have an oven hot enough, you could sinter a ceramic "felt" together to make it sturdy.
http://forum.nasaspaceflight.com/index.php?topic=27308.msg856038#msg856038

I imagine a yarn of glass for the experiment, as it softens at a lower temperature than alumina or zirconia, spun (strong gloves) under mechanical tension, and leaving big voids, on a refractory and strong mandrel - maybe a porcelain pestle can suffice. Then you heat the spun yarn on its pestel until getting a sintered part. Some unmoulding agent would be useful to recover the pestle, not easy - suppose it's lost.

Dessicated alumina powder exists commercially to be mixed with water and obtain hydrated alumina, much like plaster is used. Maybe it could impregnate the glass yarn and solidify, instead of sintering the glass or as a complement.

The obtained cylindrical shape is perfect for the use I meant, as a heat insulator around a rocket igniter inspired by Diesel glowplugs
http://forum.nasaspaceflight.com/index.php?topic=27308.msg849905#msg849905

[Enthalpy]

Could you measure accurately the density of a dozen of solid pure n-alkanes? It would be very useful if made by a single person, all with the same method and equipment.

The idea is that alkanes with odd and eleven numbers of carbon atoms show a sawtooth pattern in their melting temperature, which common theories attribute to more or less tight molecules packing in the solid, but I don't see this on the densities published by varied sources.
http://www.chemicalforums.com/index.php?topic=75605.msg274834#msg274834
(my post #2 was wrong, please forget it)

Accuracy (or rather, repeatability) like 1/5000 would be necessary, which scales and a micrometer achieve on a cylindrical shape
http://en.wikipedia.org/wiki/Micrometer
or maybe (?) you can measure the density difference with a liquid alkane by immersing the solid, poured previously in a polypropylene pot. Or adjust a liquid mixture until the solid neither floats nor sinks. In every case, the solid alkane must be separated from the liquid, or it will dissolve.

This one is true present-day research, because it tests an incomplete theory, about melting points.

[Enthalpy]

A better way to produce water ice:
http://www.chemicalforums.com/index.php?topic=46384.msg257744#msg257744
experimenting with the hands, without building any setup, is already fun. It needs a source of cold air and a pipette.

You can observe that the ice is clear, without the entrapped bubbles typical of ice cubes, and you can grow the ice quickly. Later, you can build an extensive setup. An industrial machine built that way would have a market.

A (second step?) experiment could take place within a freezer. Put an open box, a fan that circulates the freezer's air towards the box' bottom, have something (chemistry, irrigation, medicine) to drip in the box at adjustable rate; fill it with lukewarm water so it doesn't freeze there. This one doesn't need constant attention, so you can produce a good thickness.

[Enthalpy]

Draw an electrically conductive line with an ink loaded with silver nanoparticles (hope you can find it commercially), squeeze the dry line with a hammer on some anvil, observe if the resistance gets lower and more reproducible, depending less on bending and ageing.
http://www.chemicalforums.com/index.php?topic=71947.0

Printing the lines made a research paper some months ago
http://dl.acm.org/citation.cfm?id=2493486
so if hammering improves it, you can publish.

[Confusionist]

Could you measure accurately the density of a dozen of solid pure n-alkanes? It would be very useful if made by a single person, all with the same method and equipment.

The idea is that alkanes with odd and eleven numbers of carbon atoms show a sawtooth pattern in their melting temperature, which common theories attribute to more or less tight molecules packing in the solid, but I don't see this on the densities published by varied sources.
http://www.chemicalforums.com/index.php?topic=75605.msg274834#msg274834
(my post #2 was wrong, please forget it)

Accuracy (or rather, repeatability) like 1/5000 would be necessary, which scales and a micrometer achieve on a cylindrical shape
http://en.wikipedia.org/wiki/Micrometer
or maybe (?) you can measure the density difference with a liquid alkane by immersing the solid, poured previously in a polypropylene pot. Or adjust a liquid mixture until the solid neither floats nor sinks. In every case, the solid alkane must be separated from the liquid, or it will dissolve.

This one is true present-day research, because it tests an incomplete theory, about melting points.

Yes, my reason for posting in these forums was because I was looking for a chemistry related idea. They're just a lot more fulfilling, aha.

Really loved all your ideas, especially this one. This one is definitely something I know about and am interested in! The first post about finding the polymer was also doable, but I personally find this one far more interesting.   

The idea to "with a liquid alkane by immersing the solid" is definitely possible, but I think there's some logistics to figure out there...I'll talk it over with my professor and see what his thoughts are on it. He's going to want me to give him a step by step idea, so that might take a little bit to create.

Silly question: After getting all of the data, is it possible to apply this to the melting points (assuming the data is at least a little bit different from the other densities posted on other sites(?)) and begin to rethink it's correlation with melting points in terms of the equation? I know that's obviously a stretch (I imagine dozens of others have done this before and probably haven't gone that far) but if I do this, I want to try to find a way to apply it to the melting points...Is that at all possible? Ha, actually, does that question even make much sense?

edit: Page 70... http://authors.library.caltech.edu/25034/5/BPOCchapter4.pdf

Finding this already done in further depth than I'm able to go into on multiple sites. As much as I'd like to do an experiment, wouldn't it do more good to simply skip finding the densities and go right into trying to find this correlation?

Edit #2: Wait, I'm obviously missing something. Could you explain this into a little bit more depth if you get the chance? I obviously don't understand this NEARLY as well as I'd originally thought. Why would it even change anything based on the odd or even number of carbon atoms that the alkane has? I realize this is probably a very elementary question, so for that reason I tried to figure it out on my own. I took a glance at a number of articles, however I could only find the data saying that there is a difference but not why. I read your post a number of times and I still think I'm missing something VERY important and it's more than a little bit embarrassing.

[Enthalpy]

Glad that you like some suggestions!

The linked Pdf gives densities of liquid alkanes, alas... Except C₂₀ and C₃₀, both even, and too few for an observation. In fact, I'd prefer frozen C₇ to C₁₅, hence cold, because these exhibit the strongest effect on the melting point.

Other sets of data are compiled from several sources, but any observable effect would be below 0.1cm³/mol over a mean 400cm³/mol, see the third diagram there
http://www.chemicalforums.com/index.php?topic=75605.msg274834#msg274834
and for that, three digits don't suffice - but discrepancies between the authors are worse.

I had to remove two points and make a linear fit among an arbitrary subset of measures, supposedly because different authors have varied biasses - what I did overstreches the measures' accuracy quite a bit...

So I doubt that an existing set of data, accurate and credible enough, can be found. It would be hugely better that one person makes the new set with a single method, and in that case, for lighter alkanes, for which I haven't seen a set of solid densities. It requires repeatable measures only.

I've added a different measurement method there
http://www.chemicalforums.com/index.php?topic=75605.msg278590#msg278590
easier, more significant.

----------

A formula that relates the solid density and the melting point shift? I doubt it. I even suspect, after the third diagram
http://www.chemicalforums.com/index.php?topic=75605.msg274834#msg274834
that there is none, as I see no shift in the packing density for C₂₁ to C₃₀. Put a different way, the even-odd effect would not result from the packing density. Which would be new knowledge, hence the desire for data for smaller alkanes.

If you find an even-odd effect on the density, you may seek a fitted relationship with the melting point, especially if you compute the "void proportion" in the solid alkanes by comparing with the -CH₂- molar volume of long alkanes, or even the difference between two long alkanes. You then correct by the molar volume of two -CH₃, get an excess volume for the short alkanes, and seek a relationship.

[Confusionist]

Okay, I get the idea now. I pitched the idea to my professor, however what's confusing me is the process of finding these densities. I've read over your post explaining your second process idea many times and I think I'm understanding it incorrectly...Obviously, some alkanes aren't entirely safe. I realize the melting point is going to deal with manipulating temperatures, (this is more than obvious) however how much safety equipment is required, how dangerous is this, etc? Keep in mind the safety procedures of public schools...Before I even figure out the logistics of a procedure, I need to make sure it's completely safe. To be honest, I'm starting to wonder if I pitched this idea prematurely. Is my worrying silly?

[Enthalpy]

The second process measures the volume variation when the alkane freezes or melts, instead of the total volume. It's easier as it needs some 10^-2 accuracy instead of 10^-4 (my mistake).

Short straight alkanes are decently safe. They are as flammable as gasoline or as little as Diesel oil, according to their length; you could start with nonane if heptane is too volatile, but would you fear the as much flammable alcohol? You are not supposed to sniff the lightest ones for hours. Fuel vapours harm by their aromatic components, alkanes are free of them. That's all I see - maybe the chemists here tell us more.

[curiouscat]

Okay, I get the idea now. I pitched the idea to my professor, however what's confusing me is the process of finding these densities. I've read over your post explaining your second process idea many times and I think I'm understanding it incorrectly...Obviously, some alkanes aren't entirely safe.

Safety apart, how exactly are you going to cool down to say -50 C?

Do you have the facilities available at school? The other practical question for you is how are you going to go about obtaining samples of these? Note that for MP determination you'd need substantially pure samples. Sigma Aldrich might ger a tad expensive.
But not prohibitive. Depends on your budget for consumables.

[Confusionist]

Yeah, that's my next obstacle. I don't think we have those specific materials. I'm asking around and we might be able to borrow something from the local university...But this is starting to look far less feasible than it originally was.

[Confusionist]

So, if I were to go ahead and contact the local university (which I'm right about to do), what would I ask them for? Would the object be transportable?
And more questions, any ideas on what the bottle should be made of if I use the method in which you create the cavity and cool from the bottom?

[zsinger]

To truly run a probative ORGANIC reaction, one must have a full lab (University) IMO.  Many of these "experiments" use VERY strong oxidants, mutagens, strong acids and bases, etc.  One that you might run is the circuit lab from a lemon, or something with citric acid in it to act as an electrolyte.  That one is easy, cool, and all parts are available at home depot/publix.  Check Robert Bruce Thomson's book, and you may find what you seek .
        -Zack

[Enthalpy]

To chill the alkanes, I'd use dry ice in a polystyrene foam box
http://en.wikipedia.org/wiki/Dry_ice
though of course liquid nitrogen is much more fun , and available at any university
http://en.wikipedia.org/wiki/Liquid_nitrogen
chilling may then be more brutal, so a measure during slow melting would be better.

It does need a decent thermometer and practices, because 1K uniformity is desireable and not obvious.

The bottle can't be of plastic, but glass is fine, metal as well. It needs some insulation (gloves?) to catch it. Not too big a bottle, to reduce the costs: 33cL (beer) would make a 0.3cL volume variation or 0.2g, to be measured to <2mg accuracy or better. If measuring during melting, the liquid should overflow in one foreseeable direction, so it's removed instead of weighing on the scales, which suggests a bottle with a lip instead. Or maybe several bottles, because each alkane takes several hours.

Laboratory scales with <2mg sensitivity (not accuracy) and >50g range, in accordance with the bottle's capacity.

I've checked some prices for n-alkanes at Merck 2001 (as the CD still existed):
Hexane (mp -94°C) for analysis 29€/L, for synthesis 24€/L
Heptane (mp -91°C) for analysis 32€/L, for synthesis 22€/L
Octane (mp -57°C) for synthesis 14€/100mL
Nonane for synthesis 20€/100mL
Decane for synthesis 14€/100mL
Undecane for analysis 52€/100mL, for synthesis 24€/100mL
Dodecane for synthesis 12€/100mL
Tridecane for synthesis 16€/25mL
Tetradecane for synthesis 11€/50mL
Pentadecane for synthesis 23€/50mL
Merck uses to be as horribly expensive as Sigma-Aldrich. "For synthesis" uses to be 99% pure. The lab will already have some of the compounds: use a limited amount of them, and for the bought compounds, give the lab the unused amount and share the price.

This experiment takes days, but it's the opportunity for you first scientific paper. The unknown polymer instead is carried out much more quickly and would need to access some analysis equipment at the university; it's just that this polymer is probably useless, only the opportunity to run a very easy reaction and use an analysis equipment.