CaptainPanic

According to wikipedia (always a good start): Science: Engineering: Please also check out these threads (about the same topic: engineer vs. scientist). Thread 34829 Thread 38232 specifically on the topic of chemistry and chemical engineering. Personally, I believe that engineering is a branch of science... So, this means that engineers are scientists, but scientists are not necessarily engineers. I explained why I think so in this, thread (thread 38471) post #25.

I think you're well on your way to understanding at least the reactions, but perhaps not yet some definitions. What you're mixing up (I think) is: reactivity of 1 single component reactivity of 1 single component in the presence of another component (so actually the reactivity of the mixture) I think that these are two different things. And to be honest, I don't think that the reactivity of a single component is a very useful definition, unless you can identify a reaction that is likely to take place. I've never used the definitions of reactivity so much. A better description of the readiness of some component or mixture to react is the "Gibbs energy of reaction". But perhaps that goes a bit far for this moment. The message that I want to get across is that this Gibbs energy of reaction looks at the difference in energy levels of the reactants and the products. This difference is what causes the reaction to take place. Please note that this is still a bit of a simplification. I guess I should refer to a thermodynamics book for a complete and thorough explanation.

What Kaeroll means is that an "ether" is a component in which there exists C-O-C bond. This can therefore be: CH3-O-CH3 CH3-O-CH2-CH3 CH3-O-CH2-CH2-CH3 CH3-CH2-O-CH2-CH3 CH3-CH2-O-CH2-CH2-CH3 etc, etc, etc. Much more complex ethers exist, as you will find on wikipedia! (Scroll down a bit). This is a science forum after all, so this means we should be complete and thorough... this includes using complete and correct names for chemicals. But let me be kind to new people. You most likely want information about the cooling properties of diethyleteher (The CH3-CH2-O-CH2-CH3 ether)... right? So, you are now looking or endothermic or exothermic reactions with diethylether. Perhaps using the right name can help you on google/wikipedia? I'm not sure though. Since your question pretty much includes all reactions with diethyl ether (and there are probably millions!), I suggest that you still refine your question a bit more! Because as Kaeroll said: we just cannot give you a complete summary of all the reactions - there are too many! What do you want to achieve? What is the problem that you need to solve? Personally, I would think that

Could you either explain that or provide some reference? I would disagree that this is always true, and I'm not sure it's a good idea to even compare the two. There exist weak ionic bonds, and very strong covalent bonds. Nitrogen (N2), with a triple bond, has a very strong bond. If you look up the bond energy (in J/mol) and you compare it to the lattice energy of soms salts (also in J/mol), then you'll find that the bond energy of nitrogen is higher than the lattice energy of some of the salts. But I wonder if it's such a good idea to compare the two at all: - Most salts exist in a lattice, and have interactions with all the neighboring ions (both of opposite charge and similar charge). - Covalent bonds are typically between two atoms, and that particular interaction between those two atoms is typically stronger than the interactions with other atoms in the immediate surroundings. And then there are the ionic liquids, which are often organic components with lots of covalent bonds, but that also carry a charge. This causes some ionic bonds too. Bonds strength in ionic bonds also is determined by how well the lattice fits. For example, in the ionic liquids, the lattice fits very badly (so badly that it often doesn't even form, and ions move around at random). The charges cannot approach each other very well... which means that the ionic bond energy (I'm not sure you can even speak of a lattice energy here) is low. I'm sorry if I put too much info here (it's a science forum), but there are too many parameters to be able to say "this is stronger than the other".

These guys already did the job! I found the article through slashdot. Seems like they made quite an elaborate sample mechanism. The sample thingy was 459 kg!

I'm very happy to see such an initiative. It's a great step forward, and will provide valuable experience which will ultimately make future investments cheaper. I don't understand your point. So many things get government subsidy. Isn't that just normal and acceptable?

We have discussed mini-nuclear power stations just 6 weeks ago (click). I wonder if the investment is affordable for such a small and remote community as described in the article (700 people in the north of Alaska). Perhaps it is, if the scale is right, and the plant is really plug-and-play so that it can be air-lifted in and starts immediately... still, "nuclear" sounds expensive, especially in combination with "small scale". I think the idea was discussed quite elaborately for urban areas and more densely populated areas in the other thread. This deals with the world's most remote parts. (We might as well discuss nuclear power on the moon for that matter?).

It seems that managers have followed a course which told them that it's vital that all employees follow a course. At least, my manager probably did. The effect is that I have now a list of targets for this year: "Follow courses" is one of the targets. We even identified a few topics, which was very helpful if they were common topics of courses, which I think they are not. After that nothing else was said on the topic of courses. I have to find the courses that match the description that's written in the planning-form. I have found out that finding a course is actually not very easy. Our P&O department does not assist (they'll give you a name of an institute, which then lists 1000 courses). Does anyone have some practical tips how to select a course without actually having to read a million course descriptions? I'm not ready to spend more time on course-selection than on the course itself... but I also want to follow the right course, and not just any course. The name of the course does give a hint, but it's important to check the contents (the level can be too high/low, the topic just a bit different, the duration can be too long, and in my case I'd like to have the course in my own country - all these criteria make it even harder to find a course). To other working people: How do you select courses that you have to follow? Are you just told by your boss when and where to go? Or do you have to take a lot of initiative yourself, like me? Thanks in advance for any practical tips.

Reaction time can still be tested with a stopwatch... but you should build some contraption so that two people can push the button. Person 1 starts it, and person 2 has to stop it. Just an idea.

I don't have an opinion. I just felt like voting. But I didn't find that option.

The invention already exists, although in a different shape: Vacuum tube solar heaters are already used and produced on a large scale. Wikipedia also has a page about it (of course). You describe in the video that you have 10 layers of glass. These will provide a very effective insulation. The glass prevents convection (movement of air), which is exactly what you want. The commercial product uses a vacuum to prevent movement of air. If you just take a vacuum tube solar heater, and you use some mirrors to concentrate the sunlight a bit more, then I'm sure you can easily produce steam.

http://en.wikipedia.org/wiki/Ice Wikipedia shows a list of all known forms of ice. The ones that are described denser than water are formed at pressures above 300 MPa, or 200 MPa at very low temperatures. 300 MPa = 3000 bar Ordinary pipes will not withstand such a pressure... so from a practical point of view, the answer is that the ice will expand regardless of the pipe you use. Of course, pipes exist that can actually withstand this - you just don't want to buy them for normal houses. I think the solution lies in allowing the ice to expand along the lenghth of the pipe, or to use flexible materials. I haven't investigated the solution for this post (just the properties of ice).

It might help if you would say in which country, of even on which continent you live...

Netherlands also has its weekly question time, and any topic can be raised. I believe that questions can be asked to anyone in the government (all ministers, including prime minister). Opposition parties use this time for asking serious questions, and/or to get some attention from the media. And I believe that it's largely the media who can be blamed for making a bit of a circus from the question time. Mostly it's very serious though. All in all, the result of the question time is that ministers have to dodge all kinds of questions and "talk without giving an answer", but that's still better than no question time at all. That is almost impossible - you're suggesting that you want a system where a new law or policy is actually making sense for government and opposition? I'd love to see this, but it's not very realistic - governments and opposition are people. You cannot pass a law if you just admitted that it does not make sense. This would rapidly result in a system where nothing is decided at all... I think we should first start with a whole new system - in our parliament we have parties with weird programs that are based on all kinds of funny assumptions (some are even religious). Some parties cannot (ever) agree with other parties on some topics. Therefore, questions can never be answered, and there exists more than 1 truth. If politicians were all scientists and engineers, then perhaps the plan would be possible. Unfortunately, not even 10% of the politicians are actually scientists or engineers.

Wikipedia has excellent articles on these topics (and also on the differences between them). We could list all the information here, but wikipedia is better.

Wikipedia says the following about stability/reactivity: Wikipedia does not list any reaction that is likely to occur in the environment you described. I also don't know of any reaction. Are you sure that we're dealing with a reaction, and not just a puppy that wanted to chew on something? It sounds like the parts that were "eroded" were exposed to air, so some animal can have had access to it? Rats can also chew through pretty much everything.

Through slashdot I found an article that seems relevant here... It seems that there are people who spent serious time thinking about cleaning up space, and came with more realistic ideas than we did (although the laser seems quite popular - total evaporation is no option). http://online.wsj.com/article/SB123672891900989069.html

You're right, and if my previous posts suggested that I thought so, then I apologize. I was talking more about the extreme cases, but I should have made that more clear. Also, I should study those extreme cases more before I go any deeper into this topic... and therefore: I'll just link to a decent wikipedia page that describes the topic, for all to read.

Does that also mean that companies must hire stupid people who are unfit for the job? I mean, they got the diploma after all? Or is the plan that learning disabilities disappear when you're done with school? I'm working now, but learning every day. I need to read, learn, study, understand, and I even I need to do "tests" (meetings, presentations, and also classical tests with pen and paper sometimes). My university was definitely a selection. 50% dropped out in the 1st year, and a few percent even after that. The average student at a Dutch technical university needs almost 7 years to finish a 5 year study (BSc + MSc). That's selection. And that's a good thing. Our education isn't free, but it's definitely affordable for everybody.

First of all - if $17000 is a decent and reasonable investment, then this discussion is over. In the Netherlands, we have 16 million people, who live in approximately 4 million households. The expense you just mentioned exceeds the total pricetag I mentioned (4,000,000 x 17,000 = 68 billion). I guess we can agree that batteries are not only impractical, but also bloody expensive. Two points you missed: 1. In this particular thread I described hydro for storage, not generation of electricity. Please check out post #7. 2. I mentioned more than once that this is just an example of the price of sustainable energy. I totally agree that it's just stupid to use 100% wind energy because of several reasons, for example (a) the availability of other good sources of energy (b) the fact that plastics are pretty hard to manufacture from electricity © etc. Then why did I propose this? Because it's impossible to make a reasonable estimate of the more realistic but far, far more complicated scenarios.

If you make a saturated solution of potassium nitrate (meaning no more salt dissolves - warning: it's a lot of salt), and you feed that to your plant in large amounts, effectively replacing all normal water in the pot, then this salt solution will suck the water right out of the plant - perhaps not in 1 minute, but surely in about 1 hour... I've done it once, just for fun to test a massive overdose of fertilizer (potassium nitrate is a fertilizer). I got a very fast reaction, for a plant . The plant became weak, and the leaves were hanging. Depending on the plant it might even fall over. At that time I wasn't interested in how fast it goes... so I cannot remember if it happens in 1 minute (probably not)... But it's visible. But it's not really on topic, since it actually uses chemicals, not electricity (opposite from topic).

First of all, even the massive prices that you mention above (in the quote) are equal to the price of just the imported oil in those 20 years. 20 years of oil will be a minimum of 20*7.5 = 150 billion, at the current price of 35 euro/barrel! Yes, you could rebuild all those wind turbines twice for the same price as the oil imports. (Thanks for this great argument!) But I disagree with the 100 billion price tag you mentioned. It's either a lower price, and/or a longer period until you need to invest it all. Maintenance is for a good part already included in the price. And by taking large error margins in cost estimates, I tried to leave some room for more. Maintenance is not going to bring down this idea... The life expectancy is a much better point (Thanks for that! It helps the discussion!). The scheduled life of a turbine is usually 20 years... So, indeed, after 20 years, the turbines need a pretty big fix, or a reconstruction. But a total deconstruction of all of those turbines after 20 years, including tower and foundation, and total reconstruction, including new studies, paperwork and whatever is included in placement of a turbine is an overestimate. The modest inflation is a good estimate though (3% per year is within the target for the EU zone). You can rebuild the wind turbines by replacing parts. This will mean that some expensive parts can be kept. Gearbox and blades are likely to require partial replacement. Foundation and tower are just sturdy and simple, but none the less a large investment. And refurbishment keeps technology going for much longer than planned, in pretty much any case. I agree that this still has to be proven for wind turbines... but allow me to compare to airplanes: apparently, the oldest Boeing 747 is from the mid 70's. If airplanes, which are somehow comparable to windturbines, can stay alive for about 35 years with some (major) repairs, then perhaps it's not unrealistic to expect a similar case for wind turbines. Anyway, wind turbines in many locations will require a less safe operation than an airplane (because often they are in unpopulated areas, and they are unmanned machines). Those old wind turbines won't be the shiny *bling* machines they are today, but they'll work... and that's what matters.

I checked google maps, and the area seems quite tough for rail construction... so my reply will be a more general remark. Very often rail investment is compared to road investment. But rail offers some additional benefits: -Available for everybody, not just car owners -Possible use of clean energy -Less pollution even in the case of use of fossil energy -Maximum speed can be 350 km/h (though not in mountainous areas) -Lower risk: less casualties per traveled kilometer (source - check 3rd row in table) This means that investments can be higher, because you get more for the money.

We're going off topic, I know (we're done with the original issue, and it was just a joke anyway, right?)... What kind of learning disability are we talking about? I probably exaggerate here, but putting the above quote in different words: Stupid people get extra help in passing the university exams in the USA? Isn't the school system supposed to be a selection so that the right people get the right diploma to actually prove they're capable of doing the job? In my university, you got some extra time if you had a reading disability (Dyslexia)... which makes sense at a technical university, since reading isn't the most important in the engineer's life (though not insignificant either). I really hope that in a linguistics study, you actually do not get that extra time with dyslexia, for the same reason as disabled people don't get extra time on the obstable course for the marines.

You are right: the higher up in the atmosphere, the higher the pressure. That's simply because the air on the top is pushing down on the air below it (because of gravity). The atmosphere is in a force-equilibrium. While it's true that air wants to go from a high pressure to low pressure, gravity is pulling it the other way... However, if the low and high pressure are situated next to each other, like in high and low pressure regions (shown with the "L" and "H" on the weather forecast), then it will move, and you get wind. This wind can then be cold or warm, and if it crashes into another pocket of air of a different temperature, it will also get a vertical movement. The cold air, moving horizontally into the hot air is the same pressure (because it's at the same altitude) - but cold air is more dense so it will go under the hot air, effectively pushing the hot air up. This is the cold front.