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Technology / Does a steam heat exchanger remove sensible heat?

« on: 13/04/2017 23:58:22 »

We were assigned a group HW assignment that nobody (7 person class) can figure out. It starts pretty simple: Heat exchanger, saturated steam @ 200 psig, heating up process fluid from 80-200 F (heat capacity 7 J/g C), but here's the weird caveat: steam condensate returns to the steam boilers at 275 F. We've had problems where we have to calculate sensible heat loss from a pipe as a fluid returns, but could this sensible heat loss happen in the heat exchanger? As in, could the heat exchanger condense the steam and also remove sensible heat? None of us are sure if this happens in the real world.

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Physics, Astronomy & Cosmology / Does solar magnetism affect our atmosphere?

« on: 28/03/2012 18:55:06 »

I was wondering if the changing in the magnetic poles of our sun (which happens often on an astronomic scale) has an affect on the chemistry of our atmosphere. More specifically would it have an affect on the amount of carbon 14?

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Geek Speak / Does anything still use analog?

« on: 07/12/2011 04:10:36 »

So I have an old Casio keyboard and was thinking about dusting it off and using it when I noted that there is a plug in labeled "phonics/output." The port is quite large (~.5 cm diameter -circular), and I was wondering if this is an analog connection. If so, does anything use analog anymore? I thought it was a "step lower" than digital.

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Chemistry / Can one make petri dish material from pasta?

« on: 06/10/2011 16:06:54 »

After making some pasta in very little water, I noticed that what water remained after I poured it out had congealed to a jello like blob. Is this because of the starch? And if so, would this work to grow bacterial cultures?

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Chemistry / How to change Ca(OH)2 to NaOH?

« on: 31/08/2011 18:13:18 »

The title pretty much says it all, if I want to convert Ca(OH)2 to NaOH, what reaction would work? I was thinking Na2CO3 or Na2SO4, would either of those work?

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Chemistry / How to make zinc powder?

« on: 03/08/2011 05:30:58 »

I know of several ways to turn a chunk of zinc into powder: Electrolysis of a molten zinc salt; a more reactive metal in a solution of a zinc salt, taking a file to it. I was wondering if it would be possible to react zinc hydroxide with hydrogen peroxide Zn(OH)2 + H2O2 = Zn + 2H2O + O2. I know this can be done with more noble metals, but I'm not sure if it can be done with as reactive of a metal as zinc. Ideas? Any other methods?

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Physiology & Medicine / Does blood pressure affect itchiness of mosquito bites?

« on: 23/07/2011 07:14:26 »

Here in the Pacific Northwest Mosquitoes are becoming quite prevalent as the weather warms. Over the past several days I have noticed that approximately 10-30 minutes before I usually wake up my bug bites from the previous day really begin to itch. My only guess is that this is somehow connected to my body trying to wake me up at the end of R.E.M. sleep. Does this seem like a step towards the correct answer? And if so, would it be something related to blood pressure or heart rate increase?

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Chemistry / How to get silica from diatomaceous earth?

« on: 08/06/2011 04:36:25 »

I'm trying to get relatively pure SiO2 from diatomaceous earth, which according to Wikipedia (http://en.wikipedia.org/wiki/Diatomaceous_earth) is primarily SiO2, Al2O3 and FexOy. H2SO4 would remove the FexOy, but I'm wondering if it would pull the Al2O3 into solution. I suppose I could use HNO3, but I would rather not use it on something like this. Are there any other methods for purifying the silica?

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The Environment / Is it better to burn or trash Plastics?

« on: 20/05/2011 21:48:33 »

Since plastics are highly broken down by UV light, in a landfill it would take plastics an eternity to break down. On the other hand, if the non-recycleable plastics were incinerated in a high-oxygen environment, the negative effect on the atmosphere would be high, but which would be worse?

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Physiology & Medicine / What are the effects of elevation on intoxication?

« on: 30/04/2011 08:51:12 »

I have heard that elevation plays a role in the effects experienced by an individual under the influence of alcohol. Is this true? If so, are there any other compounds that would display similar effects as elevation changes?

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Chemistry / Can barium chloride (BaCl2) be made from barium sulphate (BaSO4)?

« on: 25/04/2011 05:02:33 »

I've been wondering how I could make BaCl2 from BaSO4. Wikipedia states: "BaSO4 + 4 C → BaS + 4 CO" then "BaS + CaCl2 → BaCl2 + CaS" (http://en.wikipedia.org/wiki/Barium_chloride) It states that this is performed on an industrial scale, could this be done on a minor scale, and are there any other methods?

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Physiology & Medicine / Are there synthetic bones that heal?

« on: 29/03/2011 06:43:46 »

From older topics I've read that our bone composition exhibits an excellent balance of strength and lightness, for which we have billions of years of evolution to thank. But are there synthetic bones that have the capability of healing like our natural ones, and are non-calcium based?

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Chemistry / How to precipitate ferric chloride?

« on: 22/03/2011 05:23:31 »

I have a solution of ferric chloride that is fairly concentrated, but contains a fair amount of HCl. FeCl2 is far more soluble in room temp solutions that in cold solutions so I dropped the temp to a little below 0 (C). I got a few crystals at the bottom, but after extracting them, drying them off, and placing them in a container, it turned back into a liquid. Any ideas why? Is the compound hygroscopic? Are there any other ways I can force the FeCl2 out of solution? I tried the common ion effect but for some reason it didn't work.

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Chemistry / What are good chemical filters?

« on: 17/03/2011 05:07:23 »

This question sort of spans two different topics. Agar (or agar-agar) can be used as a chemical filter for the salt bridge in a galvanic cell. It allows (for example) NO3 ions to pass through, but stops metallic ions such as Zn. What other filters would fulfill this role, and would the membrane from a plant work?

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Plant Sciences, Zoology & Evolution / What fertilizers to use?

« on: 24/02/2011 00:50:48 »

I have several potted plants, and was wondering if there was a general rule for the kind of fertilizer that should be used. Is it similar for an entire family or genus? Or is it plant specific? I'm looking for very rapid growth rate.

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Physiology & Medicine / Insulin increase in diabetics due to exercise?

« on: 03/02/2011 02:40:50 »

Does exercise have any effect on the insulin production in type one diabetics?

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Physiology & Medicine / Can type I diabetics carb load?

« on: 22/01/2011 18:54:07 »

I quite often go running with a friend of mine who is a type 1 diabetic. When I was on the track team we always had a large pasta dinner the night before competitions. Would this benefit him at all?

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Physiology & Medicine / Is bonk training advisable/beneficial?

« on: 21/01/2011 02:57:41 »

Last summer I went on a long bike ride, but carried insufficient food with me. About 10 miles from my destination I bonked. All that I can remember from those 10 miles is fading in and out of coherent thoughts/consciousness while taking back rodes to avoid traffic. Bonking is a condition when your body runs out of glycogen stores. When you bonk, your body starts burning fat, and then muscle. The September 2002 issue Bicycling magazine talked about bonk training, where an individual purposefully bonks for a short period of time in order to loose weight -fast. There is evidence suggesting that this is good for you, and evidence suggesting that this is bad for you. Since glycogen is the major food source for your brain, could this cause minor brain damage? I would like to hear the Naked Science consensus on this, good or bad for us?

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Chemistry / Acid Base problems?

« on: 15/01/2011 03:43:20 »

Obviously I am embarrassed in asking this because I always try to solve chem problems on my own, especially if they are related to school [:-[]. This wasn't assigned, but I have had a horrific time trying to align my answers with the books answer. The way I solved is below.

The Question: The base ionization constant of ethylamine (C2H5NH2) in aqueous solution is Kb=6.41x10^-4 at 25 C. Calculate the pH for the titration of 40 ml of a .1 M solution of ethylamine with 5ml .1 M HCl.

The equation needed is pH= pKa+log(Ao/HAo). pKa=-log((1x10^-14)/(6.41x10^-4))
5ml=.005 L, .005L x .1M= .0005mol HCl, 40ml x .1M=.004mol
the .0005mol HCl reacts with .004mol base to yield a (7/90)M [C2H5NH2] and a (1/90)M [C2H5NH3+], so the equation comes out to be pH=10.81+log((1/90)/(7/90))=9.965. Which is much different than the books 11.52.

I tried switching the Ao and HAo but the answer still was .3 off. Thoughts?

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Physiology & Medicine / Can blood be preserved in hematophagic animals?

« on: 09/01/2011 17:49:07 »

A while ago I read about how scientists were extracting DNA from blood found in dead fleas/lice stuck a comb that was dated to several thousand years ago. Obviously preserving blood this way isn't the best method of mass preservation as we have better methods now, but can all hematophages preserve blood like this? And if so, why? A protein in their stomachs prohibiting decomposition?