CaptainPanic

Politics has become marketing, with the big difference that it's often negative marketing. Breaking down the opponent is more cost effective than showing how good you are yourself. It's also much easier for those low on braincells, because the latter means you actually need to make sense. It's a scary development that has not yet ended. And it is happening all over the world.

Aren't we simply talking about a bottle rocket which uses steam in stead of air to push the water out?... Put the bottle rocket horizontal, and build it out of steel, and you're good to go I'd say. (Make sure by the geometry that the liquid water comes out before the steam is lost).

I think the majority of the soap will enter the glycerol phase. Fatty acids or water will also deactivate the catalyst. This slows the reaction down, or even stops it. I think that the problematic separation after the reaction is the least of your worries... A poor conversion is where it all starts. And when you wash the ethylester or methylester with water after the reaction, you still might get a stable emulsion, even when you have almost no soap. Some reactions that can occur: The triglyceride is reacting with water to fatty acids in stead of a ester (I am not 100% sure about this reaction, comments are welcome... is the catalyst needed at all, or is water aggressive enough): [ce] [Triglyceride] + 3 H2O [/ce] [math]\stackrel{cat}{\rightarrow}[/math] [ce]Glycerol + 3 [Fatty acid] [/ce] Once you get fatty acids, you deactivate your catalyst: [ce] [Fatty acid] + Metal^{+} + OH^- -> [Conjugated base]^- +Metal^+ +H2O[/ce] Note that fatty acids are present in quite huge amounts in used cooking oils. It can be as much as 30% (wt).

I voted "I'm completely disinterested in US politics", but that's just what came closest. I am disinterested in US politicians... the problem with the whole system of modern democracy is that it's all like a giant advertisement. It has very little to do with good ideas, and a lot with a good presentation of (often bad) ideas. Netherlands and Europe is influenced so much by the US that anyone here should have half a vote as well.

I would suggest learning the names of about 10-15 of them. You'll enjoy it the rest of your life. [ce]SO4^2- , PO4^3- , CO3^2- , HCO3^-[/ce] These and the ones posted by insane_alien are all very common. You might find them in any article by your local newspaper, and in any science related article. Useful to know them no matter what the future will bring for you. Wikipedia (as always) has a page on this topic. I know about 30%-50% of all names in the list they provide on the page... they're not all equally common. p.s. this topic doesn't belong in the organic chem. forum. Inorganic or general chemistry is better imho.

I think that when you compress water, and force it through a nozzle, you will actually end up heating it up. The compressor will heat up the water, and although the minimal expansion when it exits the nozzle might cool it down a bit the net effect I think is heating it up. The following formula comes from a book on homogenizers. These are used in biotechnology to break up cells (kill em!) in order to release for example proteins that are locked up inside a cell. [math] \Delta{T} = \frac{\Delta{P}}{\rho{C_{P}}}[/math] The only effect that can cause any cooling after you spray water through a nozzle is when you evaporate a part of the water. (Of course, when you have small droplets, evaporating becomes easier... but you should realize that you need a constant flow of fresh (dry) air and you will lose a part of your water). I think iNow made the best post here so far. Why reinvent the wheel? A beer tap is exactly what you want: it can cool water (beer = mostly water) in a matter of seconds. It is food-grade.

waw, room temperature? Never knew that works. The lowest temperature I tried was 54 deg C. I know that most factories that do large scale conversions do this at elevated temperature, although I found it hard to find data of individual factories (they generally don't like to say how they do things). I did this work at university, while I was a student... no clue where they get their methanol. Getting the methanol was "someone else's problem". Also no clue about the price ("someone else's budget"). It came in 10 liter containers (which is quite annoying if you only need about 80 g). Probably was lab-grade, meaning it's too expensive if you plan to make money from it.

The best option also depends a lot on your location. Is there any wind, lots of sun? I can imagine that a bit of solar power is relatively cheap in New Mexico, or Spain, but won't do much good in Alaska or Norway. I think that making hot water with a solar boiler is generally quite cheap, and relatively easy to integrate into your system (especially if you already have a water system with a boiler).

Ahmed (the topic starter) actually specified the outlet temperature. I seriously doubt that you have any control over the temperature of your water when you use a fire extinguisher, or even when you bubble liquid/evaporating nitrogen through water. I've worked on a setup which was able to cool water from 18 deg to -4 (it contained a lot of salts) in about 2 seconds. That's by using a standard liquid/liquid heat exchanger... try to beat that with a fire extinguisher. I haven't seen the mythbusters episode, but they probably wanted to keep the beer in its can while cooling it. A non-contact heat exchanger (meaning that the water and the cooling agent are not in direct contact) is definitely the way to go if you want to have something serious. (If you just want a single cool experiment, then solid CO2 or liquid N2 is probably fun if you do it safely). So, option #1 is the peltier. It does not leak, does not contain any weird gas, and consumes only electricity. Option #2 is the non-contact heat exchanger. An example is your fridge. If you were to bring the water into direct contact with the cooling elements inside the fridge, then by adjusting the flow of the water you can adjust the temperature.

Ah... my mistake. I misread the data you presented (thought you started with 125.23 vegetable oil). I think 95.8 biodiesel from 100 g rapeseed oil is quite decent... Of course, you already took into account the fact that mine was a methyl ester. By default the gram/gram yield ratio of biodiesel/vegetable oil of a methyl ester is lower than of an ethyl ester... The average molar mass of rapeseed oil is 882 g/mol. The corresponding RME is 295.3 g/mol and the corresponding REE is 309.4 g/mol. (There are a whole bunch of different chains on the triglyceride... I used data from Mittelbach's biodiesel handbook to get an average). So... let's compare your: 100 --> 95.8 to my: 100 --> 94.5 (normalized from 601.1 --> 568.3) Convert to moles: compare your: 0.113 mol --> 0.310 mol REE to my: 0.113 mol --> 0.320 mol RME Seems I have a higher conversion after all... But it's so close that we shouldn't expect that the comparison makes any sense. Rapeseed oil is different everywhere it grows, and I bet it's even different in the same place in different years. Furthermore for a good comparison, we should also compare the excess alcohol, amount of catalyst, and the reaction times. I used a 50% excess methanol. You used 23.8 g ethanol (= 0.517 mol). That's about the same excess alcohol on a molar ratio (52%). You used more than twice the amount of catalyst (per gram of rapeseed oil). What was your reaction time and temperature? I always heard that REE was a lot harder to react. But it seems you did a pretty good job.

Intro I have done several experiments making biodiesel while I was a student. Although I used methanol (not ethanol) I will post here... (I just realised that in this post I have used both the terms "biodiesel" and "RME" (Rapeseed methyl ester). In all cases I meant "RME"). Experiment / reaction I generally heated the rapeseed oil first. In a second erlenmeyer I mixed the methanol and the NaOH or KOH. Btw, To my surprise, NaOH actually almost completely dissolves in methanol. The amounts I used varied (I was studying the effect of different ratios on the conversion) but in general it was close to something like: 500 g rapeseed oil 80 g methanol (should correspond to about 115 g ethanol, if the same molar ratio is used, but I heard ethanol reacts slower... not sure though). 4 g NaOH/KOH the reaction temperature was slightly below or at the boiling point of methanol (varying between 60 and 65 degrees C). I had a thermostat,and a nice reflux cooler to keep things under control. It was all in a fume hood. Reaction time was 1 hour. Glycerol separation After 1 hour, the glycerol was separated from the biodiesel. The glycerol fraction contains most (if not all) of the catalyst. This effectively stops the reaction. Color changes The picture you have looks quite similar to results I have had. I have also observed fast color changes at the start of the reaction. The first color change I observed was the one caused by the formation of the emulsion upon addition of the methanol+NaOH (initially the methanol does not dissolve). Methanol however does dissolve in biodiesel (RME), so after several minutes (or as fast as 1 minute), the changing composition of the emulsion becomes miscible, causing another rapid color change. The solution then also becomes clear (transparent yellow). The color changes a last time to murky brown / orange when enough glycerol and RME is formed to cause the formation of a glycerol / RME emulsion. This is a brownish / orange mixture. Conversion I found that the conversion (oil -> RME) increased when a 10-50% excess of methanol was used. This has to be separated of course (by distillation) from both the glycerol and biodiesel phases. It seems that methanol has a greater affinity for glycerol than for biodiesel (RME). Washing Washing with water often formed an emulsion. I think this is actually normal. I doubt that this is because of soap present. If you use an acidic solution of H3PO4 (10% wt) for the first wash (using 1.5% wt of acidic water, relatively to the amount of biodiesel), and then wash several times with normal (demineralized water), the emulsion is less stable. Water removal (from the emulsion) Water can be removed by heating to about 50-60 degrees. In initial experiments, I used a rotary evaporator. But the emulsion was not stable, and water formed large droplets at the bottom of the flask, causing delayed boiling (not nice in a rotary evaporator). I found that (very) gentle stirring at 40-50 deg C also destroyed the emulsion. NOTE: a (yellow) transparent RME biodiesel can still contain 0.1% (wt) water. I am not sure if a diesel engine likes that. I do know that European standards say that the water content should be ≤ 500 mg/kg (EN ISO 12937). In later experiments, I first removed the majority of the water at elevated temperature by settling (settling is almost instant once the emulsion is destroyed), followed by rotary evaporation. I'm not sure how the home brewers do this actually. Results [edit] found an excel sheet with results (numbers) I'm afraid I don't know how to make a table on the forums - is that even possible? Oil: 601.1 g Methanol: 95.59 g Excess Methanol: 31.6 g NaOH: 3.9 g KOH: 0 g Biodiesel fraction: 568.3 g Glycerol fraction: 73.4 g Methanol recovered from glycerol: 12.1 g Methanol recovered from biodiesel: 19.9 g Total Methanol in mixture: 32 g Solids found: 12.6 g Total solids (est.): 15.5 g Product losses (in glassware): 13.9 Product losses (elsewhere): 0 Product losses (unexplained): -2.51 total methanol weight: 32 g methanol fraction glycerol: 0.141520468 (wt frac) methanol fraction biodiesel: 0.03383203 (wt frac) Distribution coefficient (gly/b.d.): 4.18303212 Your experiment I think the yield is quite low. Heating, stirring better, or more ethanol could be a solution to that. I also read that only primary alcohols are working. so... If you have more questions, please ask. To write this post, I dug up my old report. I know where it is now, so I should be able to answer more if you want. I did >20 experiments making biodiesel (none with ethanol though).

Direct effects on humanity 1. A portion of humanity would feel incredibly guilty (assuming that we're to be blamed) 2. All those living close to a pond finally get a decent night of sleep 3. The French would have re-invent their haute cuisine Indirect effects 1. Eco systems would get all funny with either predator or prey going missing. 2. This could lead to some other species going extinct, and some other thriving a bit too much 3. for example insects (fly, mosquito) could become a pest, and could perhaps lead to increased disease

One important question (as said by insane_alien) is whether you will get condensation or not. I think it's very common to have condensating steam in a heat exchanger (steam contains a massive amount of energy that can be transferred to the oil). Condensating steam also makes it easier to solve your heat balance. The steam will condensate on the coldest part of the heat exchanger, which is the heat-exchanging-surface. You can also assume the temperature to be constant.

Peltier is an easy way to cool (and heat) things electrically. It creates a cold and a hot surface. So, you need to get rid of the heat somehow. Also, if you're planning to make drinking water, make sure your materials are food grade.

I've voted for "other (please expand)". I have chosen for my local geographical, cultural and political situation. In the Netherlands, and in Europe, state owned enterprises used to be quite common. I think that the state should buy the energy companies, and the power-cable company (they're separate) and reform them into sustainable companies. We only privatized the energy sector about 10-20 years ago, and it hasn't brought much good regarding sustainable energy. Bringing the energy sector back under state control will come at some costs, and at the same time it will create lots of jobs. Tax money can be used. I oppose any scenario where the state simply says "it's ours now". I think we should buy it back, not take it. Btw, this is probably totally impossible in the USA, which is traditionally much more capitalistic than Europe... with much less tax income per capita. Our government has previously dealt with large projects in infrastructure that would never make lots of money. All the water works for example... Worldwide we need to reduce CO2 emissions. Locally, we might want to increase protection against the climate change (floods from rivers, sea, and/or drought). Both are projects so massive that they should be state-controlled. Perhaps even on a European level (EU).

The reaction that approaches "melting" the most because it's the transistion from solid wood to a liquid is called "pyrolysis". But it's not melting, because there are many reactions going on, and the majority of the biological polymers (cellulose, hemicellulose and lignin) are falling apart. The product is even liquid at room temperature, although the reaction typically takes place between 400-600 degrees Celsius.

Before doing anything at all, first study the following ("Study? I thought I was going into the lab"... yes: study). 1. Start with listing all the components in listerene. 2. Find out how much of each component is present in listerene. 3. Find the boiling points of all the components 4. Read http://en.wikipedia.org/wiki/Distillation - and make sure you understand it! (It's also for your own safety that you must understand it... distillation is not entirely without dangers! You will be evaporating flammable chemicals at a rate that's high enough to keep a nice fire going!) 5. Check which of the components will be the first to boil (lowest boiling point). 6. Check which is second to boil... etc. 7. Check which of the major components (present in large amounts) will be the first to boil. Try to understand what will happen when you will heat the liquid to its boiling point...

I also think that a sustainable future is no longer a technical challenge, but rather a matter is mentality and some old fashioned initiative. (It's still a challenge to achieve a sustainable future, but we have all the technology we need, we just need to implement it on a global scale)... And is North Americans would please be so kind as to stop wasting energy on the scale they're doing at the moment, we might have a few more years to implement all the things we need. So, I really hope that the dollar plummets into oblivion, which would cause fuel prices to go up a lot, especially when Arabs start selling oil in euros... (and perhaps American fuel might approach the European prices... North americans should realize that we pay well over 1.50 euro/liter... that's well over 8 dollars / gallon... North American prices are not even close to that, despite that dollar). It's funny that Americans are having "fuel efficiency thoughts" in 2008, while I think that in Europe the fuel efficiency of a car is one of its main selling points already for over a decade. (edit: I must admit that SUV's are also still too popular here... on average our cars are still a whole lot smaller, and we use a lot less energy).

Nowadays 100W might actually be able to power quite a bit of machinery. I think that if you're looking at powering a computer (something like the local village computer, giving everybody internet access) it could be worth pedaling a bit. I can't imagine anyone pedaling away on a bike-powered system in order to supply lights for the rest of the family. The following is not meant to be rude, but might be seen as such. But anyone living in Africa is generally quite a bit cheaper than most members of this forum. People might earn as little as 1 euro/day. This means that they can run a human powered system for quite some hours before it actually would become interesting to build something else. Sadly the situation is such that some people are cheaper than something as simple as gasoline, while others just burn away gasoline for fun. the only design I can imagine that might compete to cheap human (or animal) power is wind. Windpower can be built very low tech, and I think it deserves some attention. Just trying to put things into perspective... not trying to offend anyone.

Could you explain the concept of "solubility in the gasphase"? As far as I know all gases mix with each other in all compositions, and therefore nobody ever bothered to define a solubility in air. But I guess you meant the solubility of oxygen in water? I am not sure which method you use (there is more than 1), but I always like the linear ones (Raoult and/or Henry)... the magic word here is "linear". Hope that the hint is clear enough.

I've asked a friend who works in the field too... she couldn't give a product name. The mix she uses is (quoting) : Epoxy resin (5 parts), available from Merck. The hardener (1 part). A quick search on the Merck website however returned 0 hits for "epoxy resin"... Sorry that I can't be of more help.

I propose a vacuum for extra fun. If you leave it open to the outside air, the pressure would be immense. (If you extrapolate the increase in gas pressure as you decrease in height, the pressure at -10 km is already 3 bars). I was not in the mood to adapt my little model to the changing gravity as you go down, so I don't know the final air pressure, but the hugely dense air is probably as efficient in slowing you down as a 20 meter thick concrete wall... Not much oscillations. Vacuum is the way to go! Can I propose another silly idea, that might theoretically work, but that won't be built for the next 1000 years? Theoretically you can build a tunnel along the surface of the earth, and remove all air. If it stays perfectly at the same altitude, then you could put an object in orbit in that tunnel, at ground level. That'd remove the need to build passenger space ships. Just a train (with a big, big engine) would do. Funny idea, but it didn't seem worth a separate thread.

In addition to all things that have already been said, I think it is impractical to be yourself in orbit around a body, and have your power source (your "artificial sun") also in orbit. It would slowly overtake you, or you would slowly overtake the sun because the lower the orbit, the shorter the time it takes for a full circle. It would only be reasonable when either the "artificial sun" is very close to Jupiter (a very low orbit), and the terraformed place is very far... Exactly the opposite would also work (you in low orbit around Jupiter, the sun in a high orbit). The average distance to the sun then does not vary too much. For example, the distance Earth - Mars varies by a factor of approximately 5-6 if my data about their orbits around the sun is correct.

I think that it's all nicely explained on the wikipedia website: http://en.wikipedia.org/wiki/Lineweaver-Burk_plot You're probably doing this for homework, so I'm not going to give you the answers... but it's really not very hard. The equation you need to solve is: [math] V = V_{max}\frac{}{K_m + } [/math] Or (the inverse of that): [math] \frac{1}{V} = \frac{K_m}{V_{max}}+\frac{1}{V_{max}} [/math] Since you already have the plot, it is quite easy really... (You should realize that one axis is the [math] 1/ [/math] axis, the other the [math] 1/V [/math] axis... it's not a [math] X [/math] and [math] Y [/math] axis) Please note that the Lineweaver Burk plot is a linearisation, and therefore not necessarily correct... especially at low substrate concentrations.

There is nothing wrong using the football pitch as a comparison (estimating/visualizing). Where it goes wrong is that plenty of popular scientific programs fail even to mention the 4500 m2, they only mention the football pitch. And there are plenty of these units that (in my vocabulary) translate as "wow, a big number, but no idea just how big". Take the weight of the Boeing 747 (no clue, have to boot my pc, and check wikipedia), the volume of the Wembley stadium in London (again clueless, is that the volume inside the structure? Is that the total surface area multiplied by the average height?)... etc. Failing to mention the actual number and the correct units is always wrong. Which (coming back to the Mythbusters) is what the mythbusters do right: they either mention nothing at all (because they don't know), or they do give numbers and units.