AsocialSurvival
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Who is wrong, book or me?
This book says that percentage of Hydrogen in water is 10.8% by mass.
However I calculated 5.59%. Maybe author thought about presence of carbonic acid or some other impurities?
I've done this:
( (1.0079*2) / ( (1.0079 * 2) + 15.9994) ) * 100 = 5.59%
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DraconicAcid
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Quote: Originally posted by AsocialSurvival  | This book says that percentage of Hydrogen in water is 10.8% by mass.
However I calculated 5.59%. Maybe author thought about presence of carbonic acid or some other impurities?
I've done this:
( (1.0079*2) / ( (1.0079 * 2) + 15.9994) ) * 100 = 5.59% |
2/18 is more than 10%, so you are using your calculator wrong.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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violet sin
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wow, rough approximation is decisive in 3 seconds flat.
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AsocialSurvival
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Looks like i missed something. Anyway, now it's 11.19%. Who is now wrong? Maybe author thought about mineral, gas, and bacteria impurities, so it's
less H than calculated.
BTW, here's dawn so my eyes were blurry!
[Edited on 17-10-2014 by AsocialSurvival]
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violet sin
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I wasn't poking fun at ya, just noticed how quickly a rough approximation made things clear. reminded me of the chem book I am currently reading,
every set of example problems they follow up with an approximation to see if the calculated answer was in the acceptable ballpark or a logical answer.
which helps out a lot in an inquiry like this.
I have been reading this guy, got it as a gift last christmas, and figured I'd brush up on all the basics again( since it has been a WHILE since
college)
http://www.ebay.com/itm/Chemistry-11E-Access-Card-Kenneth-Go...
-Violet Sin-
[Edited on 17-10-2014 by violet sin]
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AsocialSurvival
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Of course, approximations, proportions, and comparations are always simpler to remember than exact values.
BTW, instead of opening a new topic, can somebody tell what is wrong here?
On Wikipedia article "Beryllium" heat of fusion of Be is 12.2 kJ/mol, and on Wikipedia article "Heats of fusion of the elements (data page)" it's
7.895 kJ/mol, and in that Patnaik's book above, it's 210 cal/g = 7.92 kJ/mol.
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AJKOER
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Technically, bicarbonates like NaHCO3, Ca(HCO3)2, Mg(HCO3)2, Fe(HCO3)2,.. are present in ground water, for example. There are also non-hydrogen
containing dissolved minerals especially in sea water.
These could lower the presence, by weight, of hydrogen in naturally occurring water (which has so called added 'impurities' as mentioned by the
author).
A similar comment also applies to bacteria and other organic based life forms naturally found in water (and especially sea water).
In such a case, the 11% figure, based on pure water, is too high for such water mixtures.
[Edit] I would be skeptical on the accuracy of the author's figure as it should contain an estimate of water vapor in the earth's atmosphere. In other
words, one should at least add back all the water that has evaporated that has not since returned as rain, snow,.., albeit, likely a small percentage
by weight.
Also, in the earth's crust there are many solid minerals deposits that are hydrates. Getting a good estimate of this possibly significant figure
(which actually is the main water source on the planet Mars, for example) would be hard. It may also be appropriate to add the mass of non-hydrogen
containing rock in the earth's crust, if one is counting the rock hydrates. If so, the H2 by weight I suspect would drop even further. Also, why stop
at the outer crust? Might as well take the whole planet and estimate H2 % as is commonly done for the sun.
[Edited on 17-10-2014 by AJKOER]
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Artemus Gordon
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Using figures from Wikipedia, I also get 11.19% Hydrogen. I wouldn't place too much faith in "narrative" text, even from a fairly new science book. It
may easily have been copied from some much older source, and thus be way out of date.
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