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« Odpowiedz #9 : Grudzień 22, 2011, 17:48:23 »

Dzisiaj rano na Discovery Science był kolejny odcinek z serii "Witajcie w przyszłości..." (The Future of...) pt. "Życie codzienne".
Wśród tego wszystkiego znalazł się człowiek (Dh Luise ?) który skonstruował sztuczny liść.

W wyniku tej sztucznej fotosyntezy uzyskujemy tlen który może trafić do atmosfery i wodór który może posłużyć nam jako paliwo. Krzemowe pręciki można w formie maty położyć wszędzie np. drogi, ściany, dachy, ubrania etc. Jedyny problem na dzisiaj to katalizator reakcji chemicznej, który stanowi tutaj platyna. Czyli koszty nie pozwalają zastosować tego typu urządzeń na szeroka skalę. Dh Luise zastanawia się nad zastąpieniem obecnego katalizatora czymś innym - tańszym.

W takim razie zobaczcie co o tym zjawisku pisał nie kto inny jak Michael Faraday w swoich "Experimental Researches in Electricity", już tak wcześnie jak pod koniec 19 wieku:

Cytat: Michael Faraday

300. The conclusion at which I have arrived in the present communication may seem to render the whole of it unfit to form part of a series of researches in electricity; since, remarkable as the phenomena are, the power which produces them is not to be considered as of an electric origin, otherwise than as all attraction of particles may have this subtile agent for their common cause. But as the effects investigated arose out of electrical researches, as they are directly connected with other effects which are of an electric nature, and must of necessity be understood and guarded against in a very extensive series of electro-chemical decompositions (442), I have felt myself fully justified in describing them in this place.

301. Believing that I had proved (by experiments hereafter to be described (440) ) the constant and definite chemical action of a certain quantity of electricity, whatever its intensity might be, or however the circumstances of its transmission through either the body under decomposition or the more perfect conductors were varied, I endeavoured upon that result to construct a new measuring instrument, which from its use might be called, at least provisionally, a Volta-electrometer (475).

302. During the course of the experiments made to render the instrument efficient, I was occasionally surprised at observing a deficiency of the gases resulting from the decomposition of water, and at last an actual disappearance of portions which had been evolved, collected, and measured. The circumstances of the disappearance were these.

A glass tube, about twelve inches in length and three-fourths of an inch in diameter, had two platina poles fixed into its upper, hermetically sealed, extremity: the poles, where they passed through the glass, were of wire; but terminated below in plates, which were soldered to the wires with gold (fig.16). The tube was filled with dilute sulphuric acid, and inverted in a cup of the same fluid; a voltaic battery was connected with the two wires, and sufficient oxygen and hydrogen evolved to occupy four-fifths of the tube, or by the graduation, 116 parts.
On separating the tube from the voltaic battery the volume of gas immediately began to diminish, and in about five hours only 13 1/2 parts remained, and these ultimately disappeared.

303. It was found by various experiments that this effect was not due to the escape or solution of the gas, nor to recombination of the oxygen or hydrogen in consequence of any peculiar condition they might be supposed to possess under the circumstances; but to be occasioned by the action of one or both of the poles within the tube upon the gas around them.

On disuniting the poles from the pile after they had acted upon dilute sulphuric acid, and introducing them into separate tubes containing mixed oxygen and hydrogen, it was found that the positive pole effected the union of the gases, but negative pole apparently not (324). It was ascertained also that no action of a sensible kind took place between the positive pole with oxygen or hydrogen alone.

304. These experiments reduced the phenomena to the consequence of a power possessed by the platina, after it had been the positive pole of a voltaic pile, of causing the combination of oxygen and hydrogen at common, or even at low, temperatures. This effect is, as far as I am aware, altogether new, and was immediately followed out to ascertain whether it was really of an electric nature, and how far it would interfere with the determination of the quantities evolved in the cases of electro-chemical decomposition.

305. Several platina plates were prepared (fig.17). They were nearly half inch wide, and two inches and a half long: some were 1/200-dth of an inch, others not more than 1/600-dth, whilst some were as much as 1/70-th of an inch in thickness. Each had a piece of platina wire, about seven inches long, soldered to it by pure gold. Then a number of glass tubes were prepared: they were about nine or ten inches in length, five-eights of an inch in internal diameter, were sealed hermetically at one extremity, and were graduated. Into these tubes was put a mixture of two volumes of hydrogen and one of oxygen, at the water pneumatic trough, and when one of the plates described had been connected with positive or negative pole of the voltaic battery for a given time, or had been otherwise prepared, it was introduced through the water into the gas within the tube; the whole set aside in a test-glass (fig. 18), and left for a longer or shorter period, that the action might be observed.

306. The following result may be given as an illustration of the phenomenon to be investigated. Diluted sulphuric acid, of the specific gravity 1.336, was put into a glass jar, in which was placed also a large platina plate, connected with the negative end of a voltaic battery of forty pairs of four-inch plates, with double coppers, and moderately charged. One of the plates above described (305) was then connected with the positive extremity, and immersed in the same jar of acid for five minutes, after which it was separated from the battery, washed in distilled water and introduced through the water of the pneumatic through into a tube containing the mixture of oxygen and hydrogen (305). The volume of gasses immediately began to lessen, the diminution proceeding more and more rapidly until about three-fourths of the mixture had disappeared. The upper end of the tube became quite warm, the plate itself so hot that the water boiled as it rose over it; and in less than a minute a cubical inch and a half of the gases were gone, having been combined by the power of the platina, and converted into water.

Dalej robi się już tylko ciekawiej ;-) Testuje wpływ różnych mieszanin elektrolitów, różnych substancji czyszczących, różne mieszaniny gazów, jednak najlepiej mimo wszystko działa z czystą platyną, z dobrze oczyszczoną powierzchnią, umieszczoną w mieszaninie tlenu i wodoru. Testuje też te efekty związane z temperaturą. Np.:

Cytat: Michael Faraday
341. The most favourable treatment, except or that of making the plate a positive pole in strong acid, was as follows. The plate was held over a spirit-lamp flame, and when hot, rubbed with a piece of potassa fusa (caustic potash), which melting, covered the metal with a coat of very strong alkali, and this was retained fused upon the surface for a second or two: it was then put into water for four or five minutes to wash off the alkali, shaken, and immersed for about a minute in hot strong oil of vitriol; from this it was removed into distilled water, where it was allowed to remain ten or fifteen minutes to remove the last traces of acid (318). Being then put into a mixture of oxygen and hydrogen, combination immediately began, and proceeded rapidly; the tube became warm, the platina became red hot, and the residue of the gases was inflamed. This effect could be repeated at pleasure, and this the maximum phenomenon could be producet without the aid of the voltaic battery.
342. When a solution of tartaric or acetic acid was substituted, in this mode of preparation, for the sulphuric acid, still the plate was found to acquire the same power, and would often produce explosion in the mixed gases; but the strong sulphuric acid was most certain and powerful.

Jakby ktoś chciał tego więcej, albo tłumaczenie tego na polski, to dajcie głos ;-)

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