CaptainPanic

I don`t think that`s really fair at all! I know Many home chemists (I include myself amongst them) that do this as a Hobby as well as a profession. I also class my being here at SFN a Hobby! I certainly don`t get Paid for it. so unless you know something I don`t (and by all means share it), I would avoid making such Bold inaccurate statements. Note that I believe you only qualify for 1 of the 2 points: you do stuff at home, but as you said you're a professional, not an idiot. You probably know what the abbreviation "MSDS" stands for. There are plenty of people here who don't. I said idiots who do stuff at home... We've seen plenty of questions of people who want to make a nitro-organic stuff... We've linked, attached and mentioned MSDS a lot of times. We've mentioned the word "safety" countless times in threads started by n00bs. It's just true that people can get hurt from info they get here... I know that some people have functioning fume hoods, but there exist also people who will just add a drop of water to a strong acid while staring at it from above without safety glasses. On this forum, a lot of people are just enthusiastic because they've seen stuff on youtube, and also want to do it. There are people who believe that a perpetuum motion is possible, and there are people who think that the first rocket they ever built will not blow up in their face. I'm not talking about you, YT, I am talking about people who want to make TNT in the shed without proper cooling/equipment/safety measures... they are here, on this forum. And some of them will get a Darwin award eventually.

Of course the human mind automatically likes the right angle. But that's not because of us, humans. It's because it's such a fundamental angle which occurs everywhere in nature. It's not invented by man. The only thing that was invented by man is to assign the number "90" to the right angle. And in fact, some systems assign pi/2 to it. Or 100% (for slopes of mountains (I think - not too many mountains in my country)). Also, to go back to your 1st post: why are our roads often at 90 degrees? Because that minimizes the road surface, while optimizing the surface for buildings. 90 degrees is not an arbitrary choice. It's a logical choice that follows from calculations/optimizations and also sometimes from nature itself.

Science is the pursuit of knowledge. It's idiots who use science to kill people and to make the world a nasty place. The first person who made fire might have done that for protection. Soon after it was probably used as a weapon. Is science to be blamed for that? I don't think so. Is the inventor of the internet responsible for the illegal downloads? Is the inventor of the car responsible for traffic accidents? There should be no limit to science, and in fact, there cannot be a limit. People are just too curious to have a limit. And yes, everybody in my life has influenced me on each and every possible topic. If I had lived in complete solitude, I would have been a different person. generic: age 25-30 yrs job: chemical process engineer country: see location below.

This is a science forum, not a hobby forum. People posting here are (sometimes) professionals... Idiots who try to do stuff at home will one day get a Darwin award.

Such questions are notoriously hard to answer. You probably have to go for highly polar solvents. Acetic acid might work. Vinegar (acetic acid + water) too. I have no clue how that will mix with nitrobenzene... and to be honest, I don't think you'll get an answer here... but nitrobenzene also dissolves in water, so depending on your goal, that might work? The presence of glycine in water might increase the solubility of nitrobenzene. Are you interested in the solubility in water? If you want to make a funky explosive, you might as well forget about it (anyone mentioning "nitro-something" is an explosives amateur to me). Wikipedia says that the solubility of glycine in water is 25g/100ml, but unfortunately the pH is not mentioned... and amino acid solubility in water is a strong function of the pH (meaning that the solubility can be an order of magnitude higher or lower at a different pH).

A gel requires a polymer which is crosslinked. All glycerol will do is increase the viscosity. Something which is very viscous is not yet a gel. A gel is not a newtonian liquid. Glycerol is a newtonian liquid, and ethanol+glycerol will also behave as a newtonian liquid. (Can anyone comment on this last remark? I could not find a reference, and I'm not 100% sure about it).

Well, you know the force that is available (pressure is force / area). You know the displacement, and you can estimate the frequency of the change in atmospheric pressure... so you can estimate how much power you can get from this... I suggest that you calculate it before building anything.

Paper? Most fireworks are made of paper, so it might also be good enough for you? The fact that paper can burn is irrelevant. Your rocket will burn so fast that the paper has no time to heat up. Also, the paper is insulated by the rocket fuel itself. You want to roll up many papers into one tube. Perhaps it's a good idea to attach all papers to each other with tape first? One enormous advantage of paper is that it is quite harmless in case your rocket blows up (and let me tell you that in case of a 6cm rocket, the *boom* can be quite impressive - so safety should be your top priority!). Because you will have many layers of paper, the individual fragments are very light. You'll make paper snow, which is just funny, not dangerous I would advise against the use of any metal or ceramic for a first time amateur rocket. Once you have done some tests with the rocket-fuel, and when you understand it's power, then perhaps you can work with metal. For now: safety, safety, safety... therefore paper should be your material. Paper is also easy to roll up, and therefore you can create exactly the diameter you want. Also, I advise to make smaller rockets first. 6 cm is quite large. Also, I advise to make sure that you understand how to stabilize a rocket. You don't want a 6cm diameter rocket flying horizontal in stead of vertical. A nozzle can be made out of betonite. Betonite is the stuff used for the cat litter.

The answer can be very short, or very long, as samtheflash82 already said. The famous E=mc^2 formula is the one you need to know here. E = energy m = mass c = speed of light So, this energy is indeed "stored". It's stored in the form of mass. When an atom splits, the products are a bit lighter than the original, and mass in fact disappears, and (lots of) energy is created. I probably use words which are too simplistic, but something tells me that you're not interested (yet) in the very long answer. I also advise you to click around a bit on wikipedia.

I was reading about a massive solar flare that happened in 1859. It got me thinking. Talk is that solar flares can destroy our power grid, and also computers. But would it be able to destroy a disconnected hard drive? A hard drive is essentially in a metal box, which acts as a Faraday's cage? I have a backup of most of my data on a harddrive that I don't need anymore. It's therefore disconnected from everything, and it just lies in a drawer. Is that any guarantee? Or should I really go for optic storage (CDs) to make sure I don't lose anything from a solar flare? Next week: planning to protect my data from an asteroid crash.

First of all, I would like to get a bit angry that you even think that "the scientists" are one giant conspiracy who keep all bad news away from the man on the street. I am scientist, but also the man on the street. We're trying frickin' hard to tell all the bad news to the man on the street, but all too often it's the man on the street who isn't listening. Climate change, giant garbage patch in the ocean, earthquakes in California - people have plenty of reason for mass panic, but they seem to ignore it all. Besides, the "swap" of the magnetic poles (Magnetic field reversals) is not going to happen just like that. It's not like switching the light on/off. It will happen fast with respect to the age of the earth, but quite slowly with respect to a human life. Wikipedia says the following on the topic: So make sure that you pick the right moment to panic, or else everybody will laugh at you. Imagine that you start panicking because your house is on fire, whereas in reality it might just burn down somewhere in the next millennium. But yes, some time in the future, it may be that the magnetic field is weakened and in some places negligible, and that would be a reason to take some serious measures... but panic about some slow process - humans never do that.

In addition to the points made above (that I believe to be true, but I'm not an expert): It may also be a heat-transfer limitation. The atmosphere + 30 km of the earth's crust are pretty good at keeping the heat inside.

It can happen that the reference is restricted. One should attempt to find similar info in an open source reference, but if that's not possible, then the restricted source is good enough. Better a restricted source than no source (although I also find it annoying if it's restricted - it may all be better in the future!). Personally, I have quoted in numerous cases from sources that the majority here cannot check easily. I happen to have some books which contain data that cannot be found easily online (thermodynamic data is just hard to find sometimes). In addition, I have used Dutch sources. You guys just have to trust me that I translated it (or dump it in Google translate). Personally, I think that this should be enough. Requesting that I only refer to open source information would restrict me in answering questions... which is of course not desirable.

What is there to say? I'm not sure what you want from this thread... Chemists are indeed just people. some are shy, some are totally extrovert, some never leave the house and some go out a lot and party until they drop. That goes for all scientists and engineers and people in general. Being yourself is probably the most important. There's no point in trying to become scientific as well... you can show some interest of course, but you won't become a scientist from reading here, and studying a weekend (ok, if you keep coming here every day for the next 2-5 years, then you might start to get an idea). Don't pretend that you understand science when you don't. It's usually pretty easy to find out when somebody is clueless.

Just to be on the safe side, I'd say: "At least two". Was this information useful? [Yes] [No] [i don't know]

I'll bite. So, please raise your hands - who is really, really upset that a lot of kitchen appliances are white? You have no choice in the color. It's white! Who is going to be really, really upset that a car no longer comes in black? It might make a massive difference on short distance drives, if the airco is really turned on to cool the entire interior of the car. Why do you think solar boilers are not white? It can make a 10 degree difference inside the car (??? I have no source). Let's say that the car's interior is 50 kg, and 10 deg C too hot? Cp value of "car" is 1 kJ/kgK? Then it would cost a whopping 0.5 MJ (Megajoule) in energy! Actually, I am not sure how the airco is working (what's the efficiency). A good airco is transporting heat, but does not consume too much itself. I think that realistically, you'd need to use 0.2 MJ in energy. I believe that it is the equivalent of 5 gram of diesel. Ok, so it makes a "massive" impact on the really, really short drives (less than 100 meters). then, let's address the sun that's continuously shining. Of course, the hot car is now cool, but the sun keeps trying to heat it up! We can get as much as a kW/m2. The interior of the car is insulated (I hope), so let's say that 0.2 kW/m2 reaches the inside. 5 m2 surface of the roof/windows means we get 1 kW/car. In 1 hour of driving, this is 1 kW*3600 s = 3.6 MJ (or 1 kWh). That's the equivalent of a bit less than 100 g of diesel (but if you're driving continuously, you already spent about 10 liters in that hour, so fuel consumption is 1%). The color black only increases this by a fraction. So: this new law adds less than 1% to fuel efficiency. (Hmm... Wasn't I supposed to be defending the color ban? Engineers always have to calculate ) Mods, is it allowed to calculate in the politics forum, or should we just do some civilized fighting in here? Anyway... Perhaps 0.1% fuel efficiency is worth it? Are people really going to cry over this? I admit that it's a bit childish... but how bad is it really? There are so many things where you cannot choose the color.

Why memorize when you can either derive a formula or simply look it up? Do you think that my boss gets angry at me when I "cheat" by looking up a formula because I'm not 100% sure I got it right in my head? I look up stuff every day... for work and also for posts on this forum. I remember an exam at university where I failed to memorize the formulas. The teacher afterwards told me that I did too much work to derive all the formulas... But I had to do that to arrive at the ones I needed... I didn't remember the ones I needed in the exam. I still passed. I've seen 2 types of engineers: The ones who memorize it all. they usually lack in creativity and true understanding... but can be a walking encyclopedia. Great to have those as a colleague. The ones who forget almost even their own name, but are very creative and will always exactly pinpoint the problem and solve that. The second category are the ones who are good engineers for design work (imho), if you provide them with a secretary to tell them when their appointments are.

Yes. But I think it's more exciting to watch the paint dry. In addition, I think the amount of energy that you can get from this system is disappointingly small, unless you build it at a planetary scale (but then I suggest you call it "windpower", and you should use wind turbines for it. After all, wind is caused by pressure differences).

Please, please, please, please - if you join a science forum, at least READ THE INFORMATION THAT IS AVAILABLE. I provided quite an essential bit of information which is called ***Bernoulli's equation***. You may disagree with it, fine - explain me why. I'm interested. But I'm a bit tired of being ignored, and then reading what people are guessing. I have linked not once, but twice before, in two separate posts, to the formula which clearly shows that: the vertical component does not cancel out. The accelerations cancel out perhaps, if you like to say that, but flowrate is proportional to the frickin' square root of the pressure difference between the bottom of the bucket and the outside atmospheric pressure. The hydrostatic pressure will change linearly with the acceleration of the bucket, and therefore the pressure difference changes linearly with the acceleration, and therefore the flowrate changes with the square root of the pressure difference. And that means that it does not cancel out. [math]Q = A_2\;\sqrt{\frac{2\;(P_1-P_2)/\rho}{1-(A_2/A_1)^2}}[/math] <-- formula. Read it. Source. Pressure difference (hydrostatic pressure, caused by the weight of the water) pushes the water out. The velocity of that water is proportional to the square root of the pressure difference. That means that flowrate Q is proportional to the square root of the pressure difference. It's derived from Bernoulli's equation, which is standard textbook material. I may have applied it the wrong way, but so far I'm the only one here to put up a formula... so can we please discuss that? Please note that while it's true that the average of 0 and 2 equals the average of 1 and 1, it's not true that their square roots are equal: [math]\sqrt{2}+\sqrt{0}<\sqrt{1}+\sqrt{1}[/math] This was the 3rd time I try to bring up this equation. I believe it's a vital part of the answer. Can we please use it, or find out why it cannot be applied? "Guessing" just seems a bit silly here. Thank you for your attention. Apologies for using big red letters, but I believe that YT's pictures have distracted people from my links to things that I think are important. Mods can make it less flashy if they want to.

You can probably make a closed cycle for the main components: water, oxygen, CO2, food. This should be easy. Sunlight will be needed. You just have to add a purge to get rid of all the components which will build up (which aren't broken down). This might include all kinds of components which evolve from experiments, food processing and also from humans themselves (skin cells, hairs, farts (methane)). These will not be treated easily in the main cycle, but cannot be allowed to build up. The easy solution is to simply dump this and be done... you need a relatively small amount of air for such a purge. I guess that this is what the ISS is doing... they definitely create their own clean water and oxygen... but occasionally (or continuously?) dump some air to get rid of contaminants. A purge flow and make-up (clean) flow are standard parts of a recycle in chemical industry.

The question is very hard to answer, because: 1. There exist many types of biofuel from corn: bioethanol, bio-gas (methane), bio-oil (pyrolysis oil)... so you should specify this first 2. The methods used to grow the plants (especially fertilzers), harvest the plants, and convert them into fuels really affect the efficiency a lot. 3. Climate is a big influence as well. 4. There is more than 1 type of corn, and the choice of the type of corn influences points 2 and 3. Therefore, the numbers vary a lot... and entire faculties and research institutes are dedicated to answer this question.

Polar compounds often dissolve better in water... But it's not as black and white as you thought

Partial solution follows at the end. First I have to myth-bust some bad answers. Too late. You posted on the scienceforums. It’s proportional to the square root of the force, as I’ll explain below… Water will not stay at the sides unless you spin the bucket around its vertical axis (which we don't do). Let's ignore the very last drops, shall we? Furthermore, the size of the hole is irrelevant, assuming it's the same size hole in both buckets. We're studying the difference between the two buckets, and we're looking for a qualitative answer. In this question, all that matters is that there is a hole, and that it's at the bottom of both buckets. Bernoulli As I said before in post 2: you want to study the flow through an orifice (flow through a hole)... which is a simplified version of Bernoulli's equation. The formula clearly shows that the volumetric flowrate is proportional to the square root of the pressure difference. Pressure is force per area. Area does not change, so pressure is proportional to the force of the water pressing down. Since this force is caused by acceleration, the pressure is proportional to the acceleration (gravity and acceleration caused by swinging). Conclusion so far: volumetric flowrate is proportional to the square root of the acceleration. Now we have to determine the acceleration which acts on the water, and relate that to the motion of the bucket. If the acceleration of the water is equal to that of the bucket (as it would be in free fall), then no water will come out. I'm not 100% sure at this point. The bucket moving up and down would have its acceleration average out. But since the square root of the maximum and minimum is not the same as twice the square root of the average, the flowrates would not average out. However, there is also a sideways motion which causes additional acceleration. I'm not 100% sure how to deal with this. Anyway, I hope that this helped.

For air resistance calculations, you'll need a program for "computational fluid dynamics". I do not know any such programs that are for free, but with these new keywords you might find one. Please note that even if you find the program, it's not very likely that you'll understand how it works, unless you know the physics behind it (at least a bit).

Umm, no... you're probably one of the last ones to say that on this forum :eyebrow: Everybody who is in favor of mumbo jumbo crap is either banned, or sent to the Dungeons of Pseudoscience I believe in Karma in a way that if you're friendly and good, then people will remember. Personally, I prefer to help somebody who is friendly to me rather than somebody who is not friendly to me. That probably goes two ways. So if I'm friendly, I get more from life. I know that this doesn't include all aspect of karma, but it's good enough for me.