Subject: Can someone please explain?
Posted by: Mixamatosis
Date: Jan 21 17
I've read that it's dangerous to mix ammonia and bleach. Variously I've read that it can produce deadly cyanide gas, chlorine gas (which is said to be bad for you) and even explosions.
However swimming pools are kept fit for use with chlorine, and our urine contains ammonia but then we may clean toilets with bleach. Also many cleaning products contain either ammonia or bleach and it would be easy to use them unthinkingly in combination.
How is it that people aren't generally harmed by these dangers when swimming in swimming pools or doing daily cleaning, or are we being harmed at low level and is the harm cumulative?
Posted by: Mixamatosis
Date: Jan 21 17
I've read that it's dangerous to mix ammonia and bleach. Variously I've read that it can produce deadly cyanide gas, chlorine gas (which is said to be bad for you) and even explosions.
However swimming pools are kept fit for use with chlorine, and our urine contains ammonia but then we may clean toilets with bleach. Also many cleaning products contain either ammonia or bleach and it would be easy to use them unthinkingly in combination.
How is it that people aren't generally harmed by these dangers when swimming in swimming pools or doing daily cleaning, or are we being harmed at low level and is the harm cumulative?
526 replies. On page 3 of 27 pages. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Mixamatosis 
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Hmmm. I don't think it's been suggested that victims of the current issue with paraffin based creams have been burned completely to ash, so perhaps my theory falls down there. Reply #41. Mar 20 17, 7:21 AM |
brm50diboll
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Now, to the difference between apparent magnitude and absolute magnitude: the basic idea is that the brightness of a star depends on two distinct factors. The first factor is how much light the star actually emits, which is called its luminosity. The second factor is how far away the star is. Two stars may seem to have the same brightness (and therefore the same apparent magnitude - let's say +1.0), but they are actually very different despite having the same brightness. Star A may be several times as luminous as Star B, but Star A may also be considerably farther away than Star B, so the two effects cancel each other out. The apparent magnitude scale, which depends on brightness, therefore is affected by both luminosity and distance. Astronomers wanted a quantity that depended only on luminosity. For that, they invented the absolute magnitude scale. In order to accurately calculate absolute magnitude, the distance to the star had to be accurately known, but that is the case for stars within about 1000 light years of us with today's technology. So the definition of absolute magnitude is what the apparent magnitude of a star would be if it were ten parsecs (or 32.6 light years, as 3.26 light years equals one parsec) away. Stars that are closer to us than ten parsecs have absolute magnitudes greater than their apparent magnitudes. Stars that are more than ten parsecs away have absolute magnitudes lower than their apparent magnitudes. A few examples: the apparent magnitude of our Sun is an amazing -26.7 because it is so close to us. But if our Sun were ten parsecs away, its magnitude would be only +4.8, which is visible to the naked eye, but quite dim. So the absolute magnitude of the Sun is +4.8, indicating that the Sun is actually not very luminous, compared to other stars. Now compare that with Betelgeuse. As the ninth brightest star, its apparent magnitude is +0.42 (but variable). However, Betelgeuse is over 10 parsecs away; in fact, closer to 200 parsecs away. It would appear much brighter still to us if it were only ten parsecs away. So Betelgeuse's absolute magnitude is about -5.6. Betelgeuse, as a red supergiant, is many thousands of times more luminous than our Sun. There are stars far more luminous than even Betelgeuse, but they are so far away from us that they aren't even visible to the naked eye, so their apparent magnitude is greater than +6.0, but, when corrected for their extreme distances, their absolute magnitudes approach -10. These are the hypergiants, the true behemoths of the stars. Reply #42. Mar 25 17, 11:21 AM |
| Mixamatosis
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Thank goodness Betelgeuse is not our sun. If it were, we'd be quite different I think, if we existed at all, that is. We'd either be like desert type creatures or it would be too hot for us to exist. Reply #43. Mar 26 17, 3:16 PM |
| brm50diboll
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If Betelgeuse were in place of our Sun in our Solar System, Earth could not exist. In fact, the orbits of Mercury, Venus, Earth, and Mars would all comfortably be *inside* Betelgeuse. The surface of Betelgeuse would almost reach the orbit of Jupiter. Supergiant stars are inherently unstable and fluctuate in size and brightness relatively irregularly. Interestingly, they are brightest when smallest and dimmest when largest because of temperature fluctuations at the surface (photosphere) as well. Their stellar winds are too strong for their gravity to hold, so supergiants shed a lot of mass (sometimes several solar masses' worth) in the late stages of their lives prior to their inevitable supernova explosion, which is about where Betelgeuse is in its life span now. Reply #44. Mar 26 17, 4:59 PM |
| brm50diboll
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Brian, why does the pH scale in Chemistry run from 0-14 rather than something reasonable like 0-10 or 0-100? Reply #45. Apr 05 17, 2:21 PM |
| brm50diboll
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It's a quirk of an important constant in aqueous solution chemistry (which the pH scale depends on.) The constant is known as the dissociation constant of water (or self-ionization constant of water) and at standard thermodynamic temperature of 25°C (about 77°F), it just happens to be 1.00 × 10^-14. Now the exponent of -14 is the key. All aqueous solutions, whether acidic, basic, or neutral actually contain both hydrogen ions (H+) and hydroxide ions (OH-). In neutral solutions, the two ion concentrations are equal. In acidic solutions, H+ dominates and OH- is usually vastly lower, and in basic solutions, OH- dominates and H+ is usually vastly lower. The relevant equation is: [H+][OH-]=Kw, where Kw is our constant. Now the variation of concentrations is tremendous, across several orders of magnitude, and involves concentrations in scientific notation with negative exponents, which can be difficult to conceptualize, so chemists defined pH and pOH by taking negative logarithms of [H+] and [OH-]. This converted the equation to simple numbers between O and 14. Yes, 14, because the negative logarithm of Kw (1.00 × 10^-14) is 14. The new simplified equation becomes pH + pOH = 14. If we let x be [H+] in the case of a neutral solution, then x is also [OH-], and solving the original Kw equation gives [H+] = [OH-] = 1.00 × 10^-7 for a neutral solution which then yields a pH of 7 as neutral, because the negative logarithm of 1.00 × 10^-7 is 7. So, in summary, the pH scale runs from the unusual 0-14 range because of a quirk of what Kw happens to be. If Kw had been, say, 1.00 × 10-35, then the pH scale would've run from 0 to 35. It is interesting that Kw varies with temperature, so it is only 1.00 × 10^-14 at 25°C. At other temperatures, it takes on different values, so it turns out a pH of 7 is only neutral at 25°C. At other temperatures, neutral pH may be a little higher or lower than 7 because Kw has changed. Reply #46. Apr 05 17, 2:44 PM |
| brm50diboll
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Brian, do stars rise in the east and set in the west like the sun? Reply #47. Apr 13 17, 12:31 AM |
| brm50diboll
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Not exactly, and neither does the sun usually either. If by east and west one means due east and due west, then such rising and setting is actually quite rare. But if by east and west one means only generally easterly or generally westerly, it is still not true all the time. Rising due east and setting due west occurs only for celestial bodies (sun, moon, planets, asteroids, comets, and stars) which have positions with a declination of 0°, which corresponds to the celestial equator. The sun is only on the celestial equator two days out of the year: the vernal and autumnal equinoxes. For celestial bodies located north of the celestial equator, they rise north of due east and set north of due west, and the more positive their declinations, the further north their risings and settings are. In addition, the position of their rising and settings also varies by the observers' latitudes, with more northerly latitudes pushing the rising and setting points even further north. At a certain point, if the declination is positive enough and the observers' latitudes are north enough, the celestial bodies don't rise and set at all - they remain perpetually above the horizon and are called circumpolar. The most famous circumpolar star is Polaris, the North Star. The Sun itself remains perpetually above the horizon in the Arctic for varying numbers of days (depending on the exact latitude) during the Northern Hemisphere summer. Of course, the situation is exactly reversed from the point of view of Southern Hemisphere observers. A celestial body that is circumpolar in Los Angeles never rises at all and stays perpetually below the horizon in Wellington, New Zealand. And, for celestial bodies with negative declinations, again, everything is reversed, with rising and setting now south of due east and due west and becoming more extreme the more southerly the observers' latitudes. Alpha Centauri has a very negative declination. In New Zealand, it is circumpolar, staying above the horizon perpetually. But here in Longview Texas, Alpha Centauri stays below the horizon perpetually and never rises, so I have never seen Alpha Centauri, even though it is the third-brightest star in the night sky. The second-brightest star, Canopus, is just slightly more northerly in declination (less negative) than Alpha Centauri. From Longview, Canopus does rise, but barely. It rises in the south-southeast and skims the southern horizon less than 5° at maximum altitude, then sets in the south-southwest about four hours after rising. But from locations even more northerly than Longview, Canopus, like Alpha Centauri, never rises. So no, not everything in the sky rises in the east and sets in the west, at least technically. But nothing rises in the west and sets in the east on earth. You would have to go to Venus, say, for that, since Venus's rotation is retrograde (backwards.) Reply #48. Apr 13 17, 1:01 AM |
13LuckyLady
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Brian, are you posting to yourself? Reply #49. Apr 13 17, 3:47 PM |
| 13LuckyLady
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Brian, what is a blue moon, a harvest moon and a hunter's moon and how often do they appear? Thank you in advance.... Reply #50. Apr 13 17, 8:44 PM |
| brm50diboll
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Yes. I am posting to myself. But if someone else (such as yourself) asks a question, I am happy to interrupt my monologue to myself to answer it. The reason I post to myself can be found in posts #36 and #37 on page 2 of this thread. Now, to your questions, which are excellent: a blue moon is a second full moon in a calendar month (usual definition - there is a secondary definition I won't get into at this point.) Full moons occur about every 29.5 days. But most months (sorry, February) are longer than that, so full moons tend to occur slightly earlier each month than the last. If a full moon falls on the 1st (possibly the 2nd), then another full moon may occur on the 30th or 31st. This rare second full moon is called a blue moon. The exact reason why is not clear, as blue moons are no bluer in appearance than any other full moon. But "blue moon" is a metaphor for a rare event, because they occur only about once every three years on average (February can complicate this.) The harvest moon is the moon nearest the autumnal equinox (approximately September 22) in the Northern Hemisphere. Because of its rising positive declination in the subsequent next few days following the harvest moon (it is difficult to explain "rising positive declination" without a long and arduous digression into astronomy, but trust me), the almost full waning gibbous moon is especially prominent those next few days after the harvest moon, which traditionally gave extra light to farmers after sunset for the fall harvest. This only works in the Northern Hemisphere, though. In the Southern Hemisphere, the "harvest moon effect" would be due to a "falling negative declination", and would occur in March, but the September full moon (once a year) is traditionally the harvest moon. The hunter's moon occurs one month later than the harvest moon (typically in October) and has a slightly less prominent effect (as the positive declination rise is less marked in October than September in the Northern Hemisphere) that traditionally got its name for providing extra light after sunset for a few days in fall to aid in hunting. It also occurs once a year (usually October, but occasionally early November.) I hope my answers were helpful. To explain "rising positive declination" would require first explaining what declination is, a term I've used before. I think I'll do that some other day. But here's the short version: declination is to the celestial globe what latitude is to the globe of the earth. When talking about positions on the earth, we say latitude and longitude, but when talking about positions in the sky, we say declination and right ascension. Reply #51. Apr 14 17, 7:59 PM |
| brm50diboll
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I apologize, 13LuckyLady, for taking so long to respond to your questions. I was working very late yesterday and did not see your posts until tonight. As Mr. Spock said to Captain Kirk in the Star Trek episode "Errand of Mercy": "I endeavor to be accurate." Simply citing the dictionary definition is not how I do things; I put real thought and effort into my answers to questions, which can be time-consuming (sorry to complain.) Reply #52. Apr 14 17, 8:15 PM |
| 13LuckyLady
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No worries... Never hurry on my account. Your responses are well worth the wait. I, equally, took time deciding what questions to ask you. A nice respite from a busy day. Thanks again! Reply #53. Apr 14 17, 8:27 PM |
| 13LuckyLady
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Keeping Sci/Tech in the limelight, Brian? Excellent! I plan to ask another question....now to find just the right one. Reply #54. Apr 14 17, 8:29 PM |
| brm50diboll
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The questions I ask myself are deceptively simple questions that turn out to have complicated but logical answers when explained. I'll be waiting for your questions, and I invite anyone else who wishes to ask a Sci/Tech question to ask one. If I don't know, though, I will admit so. Reply #55. Apr 14 17, 8:58 PM |
george48
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If you want deceptively simple questions, here is one for you; Why is the sky blue and grass green as opposed to the other way around? Reply #56. Apr 14 17, 9:23 PM |
| brm50diboll
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Fantastic questions! I was going to ask myself why the sky is blue if no one else did, but be warned: the answer is complicated. First, a little debunking of "old wives' tales": the sky is not blue because it "reflects the oceans". The short buzzword answer is: Rayleigh scattering of sunlight. This is rather complicated to explain. Where to start? Well, the exact order is not that critical, but I do need to hit all the major points of difficulty. First, sunlight is a mixture of the colors of the spectrum (ROYGBIV), but, it turns out, the *amounts* of the colors are *not* equal. Sunlight contains more green light (in the middle) than any other color. The further from green you get, the less of that color, with violet being the least common color in sunlight. Next, human color vision is based on three "cones" which perceive red, green, and blue, but again, our degree of color perception is not equal for all colors. We are actually *most* sensitive to green, and fairly insensitive to violet. Then, Rayleigh scattering is a variant of refraction of light, but is sensitive to which gas or gas mixture the light is passing through. In the case of earth, the atmosphere is predominantly diatomic nitrogen (N2). Light rays are bent (refracted) as they pass through our atmosphere. Shorter wavelengths are bent more (at higher angles) than longer ones, a phenomenon called dispersion, which is particularly noticeable when drops of water act as prisms to produce rainbows, but, in the absence of water, blue and violet light are scattered at high enough angles to be scattered through the sky. Since there is more blue light than violet in sunlight, and since our eyes are more sensitive to blue than violet, we perceive these short wavelength, highly scattered colors as "sky blue". The longer wavelengths of light are scattered at lower angles, but if the sun is low in the sky, as near sunrise or sunset, then these longer wavelengths may be scattered through the atmosphere, which is why the sky near sunrise or sunset appears orangish. Furthermore, particulate matter present in the air alters the refraction pattern, so if there is dust, smoke, or smog in the air, the sky appears reddish, especially when the sun is low in the sky. Now, contrast this with Mars, which has a very thin atmosphere composed primarily not of nitrogen like Earth, but carbon dioxide, and also contains a significant amount of very fine suspended ferric oxide (rust) dust in its atmosphere. The physics of Rayleigh scattering in the Martian atmosphere is so different from what it is on Earth that the color of the Martian sky is dramatically different, a salmon-pinkish color. Clouds are white because they add an element of sunlight reflection, not refraction to the situation, and reflected sunlight is white. Haze is similar to clouds, consisting of extremely tiny liquid water droplets finely scattered high in the atmosphere, and its reflective "whitening" effect bleaches out the normal blue color of Rayleigh scattering, so on hazy days the sky color is much a much paler, almost whitish blue. I will answer the second question in the next post. Reply #57. Apr 14 17, 9:53 PM |
| brm50diboll
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Grass is green, just as leaves of most plants are green, because of the presence of the extremely important pigment chlorophyll, which is used for photosynthesis. Now, chlorophyll absorbs sunlight to use its energy to "split" water molecules into hydrogen and oxygen and put highly energetic excited electrons into an electron transport chain for use in synthesizing sugars, but, chlorophyll does *not* absorb all wavelengths of light equally. Even though green (as stated in the last post) is the most common color of light in sunlight, it turns out that chlorophyll is a very poor absorber of green light. There are actually two variants of chlorophyll found in plants known as chlorophylls a and b, with slightly different absorption spectra, but both forms absorb red light most strongly, and violet light secondarily, with little absorption of green light, despite the fact that green light is the most common type of light present. The reason for this is in the physics of the conjugated porphyrin ring surrounding the central magnesium ion in the chlorophyll molecules: they are just not well-suited to absorbing green light, unfortunately. As a result, green light cannot be utilized well at all by plants for photosynthesis, and plants removed from sunlight and placed under artificial green lights will eventually wither and die. Shocking as it is, plants *hate* green light because they can't absorb it or use it well. We do not see the light plants absorb, which is predominantly red, we see the light plants plants don't absorb, and that is the light they *reflect* away, because they can't use it. Chlorophyll reflects away green light, hence, plants are generally green. Now, chlorophyll is not the only pigment present in leaves of plants. There are others, but they are usually "masked" by the overwhelming amount of chlorophyll present in plants during the growing season, when photosynthesis is most active. But in fall, chlorophyll is the first pigment to be broken down, thereby "unmasking" the other pigments, which are retained longer, leading to other colors appearing in the fall. Some of these other non-photosynthetic (at least directly) pigments include rhodophylls (red), carotenoids (orange), and xanthophylls (yellow). An interesting experiment done in high school AP Biology labs is to extract chlorophyll from leaves into an ethanol solution, then shine UV light into the extracted chlorophyll solution, because chlorophyll is actually fluorescent. But it does not fluoresce green, it fluoresces reddish-violet. The kids love seeing the color change from green in normal light to red in UV light. Roses are red Violets are blue Color is complicated Do you think so, too? Reply #58. Apr 14 17, 10:19 PM |
| 13LuckyLady
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Were your answers helpful? Yes! "declination and right ascension".....brain food! Next question... The moon is purported to affect mood in humans. Factual or merely a way to explain human behavior? Reply #59. Apr 15 17, 8:16 AM |
| brm50diboll
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You're probably not going to like my answer on that. I haven't read anything convincing to me on that question. A great deal of anecdotal stuff, which is not totally useless, but anecdotes are useful mostly as examples of a point you're trying to make rather than justifications for it. Culturally, the moon has been important since prehistoric times. The whole concept of a "month" originally derived from the lunar cycle. So many people are strongly convinced the moon influences human behavior. The moon definitely influences tides,and because of its light, it is reasonable to conclude humans are more active on moonlit nights than when the moon is absent from the sky, but while SAD (seasonal affective disorder) is a well-documented emotional phenomenon associated with sunlight deprivation, I'm not convinced of any valid mechanism (speculation on melatonin or other hormones), that the moon influences human emotions. The gravitational force exerted by the moon on a single human 238,000 miles away is utterly negligible. Your chairs exert more of a gravitational force on you than the moon does. And it appears to be coincidental that the human female menstrual cycle averages about 28 days. Certainly it is not aligned with the phases of the moon in any way, although the spawning of certain corals is known to align with full moons. Reply #60. Apr 15 17, 9:31 AM |
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