Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Unregistered on December 13, 2009, 05:56:21 PM
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Hello, does anyone know however scientists managed to prove at the time we splited water in dihydrogen and oxygen, that some substances were not molecules but unsplitting atoms?
At this time, I don't believe they used very technical means to end to that conslusion.
And yet what it's teached in high school doesn't prove anything, my classmates nodded, damn it's not catechism !
My problem is that I see all that haven't been proved to myself, as questionable.
I'm always wondering how did they do ? How could we dispute it if nobody knows how they did ?
All I managed to find out in Internet is almost word for word the same thing inculcated in classroom.
What an elite of thinkers they've made ! School need deep reforms at least in my country! I'm fed up
buying and reading expensive books to fall on the same murky stuff. Please could someone help me before
I get into a nervous breakdown.
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I am not sure I understand your question - but I think they have not proved it at the time, that was just the simplest explanation, one that get confirmed later.
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Perhaps it had been a lame theory for a long time. But sooner or later it had to be proved, you can't get away with it ;).
If you had a new substance, (which you want) outcome from another and you had to prove you can't break it down longer,
that body is only compounded of the same sort of atom, no molecules, in order to work out the atom theory, how would you do ? Because all that list of elements which we can forecast stochiometric stuffs now, has been worked out from the certitude that
they were atoms and nothing else and necessarily before Mendeleiv was born and found rules for elements. So any help would be welcome. I will do more researches and tell them at the same time, maybe I've got a clue :)
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How do we know the amount of atom in a mol ? what a headache, they used microscopes ? oO
My book just tells who's wrong and why. Awesome ! now I'd like to know why we are right ?
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How do we know the amount of atom in a mol ? what a headache, they used microscopes ? oO
My book just tells who's wrong and why. Awesome ! now I'd like to know why we are right ?
Well could you define what is a mole?
Then I'll answer you ;D
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How do we know the amount of atom in a mol ? what a headache, they used microscopes ? oO
My book just tells who's wrong and why. Awesome ! now I'd like to know why we are right ?
Atoms can't be seen using an optical microscope.
I found a webpage http://www.westminster.edu/acad/sim/pdf/SDeterminingAvogadro_001.pdf that you may find interesting. :)
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Atoms can't be seen using an optical microscope.
I found a webpage http://www.westminster.edu/acad/sim/pdf/SDeterminingAvogadro_001.pdf that you may find interesting.
Thank you cth, indeed that's interesting. Savy2020 first prepare your answer and maybe I will take trouble to explain you what is a mole. Finally I don't need to know, there will always be something I'd have to trust without being able to prove it or even understand anyway I hate chemistry for that, that's why I give up school 6 years ago. I don't believe you all ! However I've got the doublethink I can use knowledge even so. Damn I'm drunk, I've found out that turtle heart still throbs when you cut it off, so cute ! I bet nobody knows how ATP has been discovered, they blindly trust !
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http://lmgtfy.com/?q=determination+of+avogadro+number
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Thank you Borek I know how google works !
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Unregistered, go get this book: "A Short History of Chemistry" by Issac Asimov. You can probably check it out from your library and read it in one or two afternoons. It will answer all your questions about who discovered what and how these discoveries led to our modern day conclusions...and it does so in a simple and elegant way.
The reality is that when these things were originally discovered things WERE very much up for debate. For example, when Dalton proposed the molecular formula for water he proposed that it must be HO. His evidence at the time led him to believe that. Later evidence concerning electrolysis of water led to the modification that made it H20 as there were two volumes of hydrogen gas released for every one volume of oxygen. Knowledge isn't built in a day, but over many years and we are continuing to refine our views. For this reason, short explanations of "how we know" are not possible. Asimov's book is the closest thing I have seen to a short answer to questions of this type.
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Thank you renge ishyo, I will go and get this book. I've got one like that but it's rather biased towards industrialization. Two volumes of hydrogen released, Avogadro and Dalton were of the same generation, they might have worked together and discovered it sooner without electrolysis if it might occur their mind that water could be H2O. My first question is still unresolved, even if following experiences have merely confirmed the composition of substances as water, I still think that some major experiences have allowed us to define elements with certitude. I can't imagine scientists think "as far as we know, we haven't managed to decompose that stuff yet and in so far as we don't even know at all what it is, let's assert it's an element until detractors crop up" that sounds wrong. I just seek to gain an insight.
Have atoms got any testable property that molecules haven't ? oO
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I can't imagine scientists think "as far as we know, we haven't managed to decompose that stuff yet and in so far as we don't even know at all what it is, let's assert it's an element until detractors crop up" that sounds wrong.
That's exactly how it worked. Some substances were considered elements before someone found a way to decompose them, or to show that they were in fact mixtures.
Have atoms got any testable property that molecules haven't ? oO
Yes, they can't be decomposed. That was the only property they were able to use.
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I can't imagine scientists think "as far as we know, we haven't managed to decompose that stuff yet and in so far as we don't even know at all what it is, let's assert it's an element until detractors crop up" that sounds wrong.
It is possible to prove that a theory is wrong by doing an experiment that directly contradicts it.
However, it is impossible to prove experimentally that a theory is right. You may do thousands of measures that prove it, yet you can't be absolutely sure the next experiment will confirm it...
To make it simple: scientist propose ideas, theoretical models... and check them in the lab. If all the experiments are conclusive, the theory is validated beyond reasonable doubts. For example, you have dead theories that were accepted for a long time, like the phlogiston http://en.wikipedia.org/wiki/Phlogiston but have been proved wrong.
An example of incomplete theory: Newton theory of gravitation has been working perfectly to describe motions from apples to planets... It was confirmed by countless measurements. And yet, it was incomplete, as shown by Einstein relativity. Similarly, relativity and quantum mechanics have been confirmed experimentally many many times. Yet, those two theory contradict each other when you try to use them together --> both are obviously incomplete as well. But the unifying theory has still to be worked out... So, we have to make do with those theory before getting a better one.
At best, a theory is only valid beyond reasonable doubts, not more:
- a good experiment is the one that invalidates your model, forcing you to move forward with a better one.
- a good scientist is someone who tries hard to break down his own theory and model! Not someone who tries to prove them.
The mindset of trying to break ones own work to see how robust it is, is not natural. As human, we would rather try to protect it. I see it as the main reason why religions (where you try to protect the dogma, no matter what) have been around for thousands of years while science is a new comer a few hundred years old.
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It is possible to prove that a theory is wrong by doing an experiment that directly contradicts it.
However, it is impossible to prove experimentally that a theory is right. You may do thousands of measures that prove it, yet you can't be absolutely sure the next experiment will confirm it...
As Feynmann put it in his lecture - we can't be right, we can be only wrong :)
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That's exactly how it worked. Some substances were considered elements before someone found a way to decompose them, or to show that they were in fact mixtures.
Seriously ?! But now we don't do that anymore concerning new substances, I hope ! Somehow we can check. Maybe not. It doesn't makes any sense I can't think that from them.
Phlogiston theory was a good theory except for the thousands of witches which must have served as measure, that's a shame we let it down. I find today's theories more nihilist, colder, there's vacuum everywhere, we've reached the end of the beginning !
we can't be right, we can be only wrong
I will wait till they find something right then. :)
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I can't imagine scientists think "as far as we know, we haven't managed to decompose that stuff yet and in so far as we don't even know at all what it is, let's assert it's an element until detractors crop up" that sounds wrong. I just seek to gain an insight.
Yup, that IS the thinking (or what the thinking "should be" anyways). Scientists do experiments. The results of those experiments either support or contradict existing theories. When they contradict existing theories, then new theories have to arise that cover both the old and the new observations. Then these theories are tested against future experiments until some experiment comes along to challenge it, and so on and so on, etc. In other words, science isn't a static thing...it changes with time. Our "view of the world" changes with time along with it. The science of the 1700s is not the science of today. "The truth" from science in the 1700s is not the same "truth" of today (unless you consider that the truth of science was never meant to be absolute, which it isn't, in which case you would say that the truths of the past have merely been modified several times over to account for newer experiments).
We tend to overlook this even now (but Asimov doesn't, hence the value of his books!) when we describe science because it makes us feel better to believe that what we understand at present is "the absolute truth". For example, we claim that Democritus discovered the atom in ancient Greece, and that Dalton "proved it," and from then on the idea was accepted as "a truth" by scientists in happy harmony. It was simply not so. In fact, it was not until the early 1900s, when experiments started to demonstrate the structure (and substructure) of the individual atoms making up matter, that thinking about atoms became mainstream. There were MANY scientists in the late 1800's that fought bitterly against atomic theory, and some refused to accept it outright even into the 1900s. This came from the prominent discoveries of the past, which these sceintists were having a hard time letting go of. One such example was that of electricity. Benjamin Franklin imagined electricity as a continuous fluid, and not as an assemblage of discrete particles. Fluid theories were popular and existed in other forms such as the "caloric" for energy and theories at the time had to be explained in terms of a fluid being continuous to even be generally accepted...whether or not the experimenter believed that matter was continuous or not. This was part of the reason that Arrhenius graduate thesis in 1884, on the existence of "ions" in solution to explain electrical conductivity, was not only opposed at the time...he barely graduated with it (with the lowest possible distinction) despite the fact that it was argued so well that nobody could really oppose it. Now it is accepted (and Arrhenius got the nobel prize in 1903 for his ionic theory once some of the evidence that matter was particulate in nature had come streaming in), but at the time this line of thinking was frowned upon.
Perhaps one day our modern view of atoms will be gone (!) and we will be describing interactions between some new type of thing smaller than an atom (or perhaps, larger!) that someone will describe that can make sense out of quantum mechanics (but even to do that you have to overcome the modern thinking that quantum mechanics is "supposed" to not make sense by its nature...a philosophy put forth by Bohr and company largely, in my view, in an attempt to protect their theory from future theories and advancements). To do anything like that, you have to wait on the results of experiments. At present time, physicists are waiting for data from the Large Hadron Collider to see if the data that comes out supports our modern views of quarks and whatnot or if it opens the door to some new understanding that we can't really anticipate at present (actually we are merely waiting to see if the thing will ever even work...but it sounds more exciting to say it the other way ;).
I will wait till they find something right then.
Even if our modern understanding of science is incomplete, taken as a whole you can use it to predict things. There is its value. Any branch of knowledge has its value in this sense; the ones that are the most accurate in their prediction of the results are the ones we depend on the most when we go about influencing our lives. Even wrong theories like the Phlogiston theory that are thrown out to make way for new ones were useful at the time because they helped thinkers predict and understand what it was they were trying to do at least in some cases. If you are waiting for the "absolute truth" to come along so that you never have to refine your views, you will be waiting (in complete ignorance) for a long time. We don't have it, and I don't think we ever will (but then again, this is just my opinion...).
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I personnaly feel much better to think that's not the absolute truth, that theories could be not as definite as I thought, thus it set scientists down closer to my level in my mind, and further from the truth. It's less frustrating.
Light theories are strange, wether corpuscules or waves, what has followed is that we finally use both depending wether it suits or not, as far as I know. Rules out from observations might suffice to forecast in some cases, especially in this case because we tend to describe it with a mechanic way, and it requires to materialize light as a substance, how else could we visualize it than our mind is allowed to ?
Now I feel less bound to study theory, moreover not believing people, now, I believe they are always out of truth and that they could wait datas for long time ! Thank you renge ishyo and all others for your answers :)
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Phlogiston theory was a good theory except for the thousands of witches which must have served as measure, that's a shame we let it down. I find today's theories more nihilist, colder, there's vacuum everywhere, we've reached the end of the beginning !
Phlogiston theory has been experimentally proved to be wrong, so it is not a good theory. You may like the aesthetic of it and want to keep it, but nature doesn't have to follow your way. Quite the opposite.
Personally, I find today's theories less nihilist and cold than previous ones.
- Gravitation from Newton point of view is fully deterministic: if you know the state of the system at one time, you can calculate it at any time in the future. There is no escape. You'll become what you were meant to become. No free will.
- Quantum mechanics has introduced a part of indetermination, of probability. With it, free will becomes possible (wether or not it actually exists is another matter).
Light theories are strange, wether corpuscules or waves, what has followed is that we finally use both depending wether it suits or not, as far as I know.
Quantum mechanics is very strange indeed. But, if you consider nature to be homogeneous, then it only makes sense that corpuscles, waves and energy are different sides of the same coin. And can be interchanged. A bit like height, width and length of an object can be interchanged, depending how you look at it. Wouldn't it be strange afterall if corpuscles and waves obeyed two separate physics? Like two parallel universes that interact closely and yet are different.
Now I feel less bound to study theory, moreover not believing people, now, I believe they are always out of truth and that they could wait datas for long time ! Thank you renge ishyo and all others for your answers :)
Yet, you need to study scientific theories if you want to know what are their strengths and weaknesses, to have a clearer view of the world you're leaving in and to have a better understanding of current debates such as climate change, nanotechnology safety,... Just remember that nothing in science is set into stone, everything has to be proved again and again...
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Quantum mechanics is very strange indeed. But, if you consider nature to be homogeneous, then it only makes sense that corpuscles, waves and energy are different sides of the same coin. And can be interchanged. A bit like height, width and length of an object can be interchanged, depending how you look at it. Wouldn't it be strange afterall if corpuscles and waves obeyed two separate physics? Like two parallel universes that interact closely and yet are different.
And to predict what would happen, you toss the coin ?! You're an illuminate blind by the aesthetic of the light theory and of the interchangeability of thought, the two work because they are two half-wrong theories.
Yet, you need to study scientific theories if you want to know what are their strengths and weaknesses, to have a clearer view of the world you're leaving in and to have a better understanding of current debates such as climate change, nanotechnology safety,... Just remember that nothing in science is set into stone, everything has to be proved again and again...
Climate, cristallization of snow flake, currents, despite all that really interest me, I gotta choose. I could ever get some words about in a review. I know all sciences overlapped but I need to be involved in what I learn. Experiments interests me much more than predict things only from "stolen" knowledge, I prefer staring at cells under microscope and think for myself. I can't be involved in all anyway. Otherwise from link to link I end on a chemistry forum been talking to you :).
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And to predict what would happen, you toss the coin ?! You're an illuminate blind by the aesthetic of the light theory and of the interchangeability of thought, the two work because they are two half-wrong theories.
I disagree with what you wrote, waves and particles are not two wrong parts that happen to cancel out their respective problems.
Quantum theory is uniform and should not be seen as two different parts brought together with some glue. And it is a very strong piece of work that has faced so many experimental trials and always succeeded to predict their results with outstanding precision. You can rely on it when you do theoretical chemistry calculations.
You don't like it because, for some reason, you are unsettled by its results. And, instead of working out why you have such prejudice, you prefer rejecting it outright. This is very unscientific.
I am illuminate? Maybe, but at least I have the light of reason and logic to illuminate my path. As you are in the dark with only your prejudices to guide you.
Climate, cristallization of snow flake, currents, despite all that really interest me, I gotta choose. I could ever get some words about in a review. I know all sciences overlapped but I need to be involved in what I learn. Experiments interests me much more than predict things only from "stolen" knowledge, I prefer staring at cells under microscope and think for myself. I can't be involved in all anyway. Otherwise from link to link I end on a chemistry forum been talking to you :).
You're using a computer regularly. Yet, have you experienced yourself with how a transistor work? Have you studied in detail in the lab how radio waves work? Yet, you're listening to the radio sometimes... Do you intend to redemonstrate to yourself everything about everything? If true, you'll die of old age before you're done with it.
Personally, I haven't tried to redemonstrate in the lab the examples I mentioned above. I am happy to use this knowledge, brought by smart people who knew their subject better than I do.
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I don't reject theories because they settle me, but because I'm bound to trust others about what I could never verify. That's not unscientific that's just asocial. Yes I'm trying to cope with making fire in the dark to prove to myself I would be able to find it out as well while you go on your marked out path.
You're using a computer regularly. Yet, have you experienced yourself with how a transistor work?
I started learning informatic when I was 13, I've skipped classes for it, I've programed for several years gradually I become interested by hardware functioning, and I feel bound to learn it, then by electronic afterward physics and chemistry feeling how much I was depending on others and that all my world could fall down if industry decided to stop working on and which could make all my knowledge worthless and as a waste of time. Now I don't care anymore because somehow I hate computers, industrial and demographic rise and globalization which is jeopardizing our world (some hope for copenhague :-X). it's possible you set another milestone some day but I need to get my own way.
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I don't reject theories because they settle me, but because I'm bound to trust others about what I could never verify. That's not unscientific that's just asocial.
OK, I see I had misinterpreted your words. Sorry.
Good luck if you need to spend much time to redemonstrate everything. This is good practice for learning, but it saves time to accept someone else results: I can't see myself reproducing the results of every scientific publication I read daily... I would have no time to do anything new. One has to trust that authors and paper referees have done an honest job. It's the only way.
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It's the only way.
Yes I'm realizing I must get rid of that, which is a great step forward into mankind ! Thank you, anyway.