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При обжоге 300 г известняка получили 140 г оксида кальция.Вычислите массу и массовую долю карбоната кальция ,содержащегося в известняке .Заранее благодарствую
:)
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выручаешь, спасибо!
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Автор:
maraayers - 5 лет назад
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Дано:m(смеси)=300гm(CaO)=140г_________________m(CaCO₃)=?W(CaCO₃)=?_________________ m 140CaCO₃→CaO+CO₂ 100 56m(CaCO₃)=100*140/56=250гW(CaCO₃)=m(CaCO₃)*100%/m(смеси)W(CaCO₃)=250*100/300=83.33%
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Автор:
kaitlinvbwh - 5 лет назад
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The First Cinema Films.
One of the first cinema films was made by Edison, but the intervals between his photographic exposures were too short - about forty-eight photographs taken (and shown) to the second. The human eye could not see them so fast and the movements therefore appeared very jerky. This made the eyestired.
When Edison's machine was brought to France to show films, it was seen there by Auguste and Louis Lumiere. These two brothers soon made a camera and projector that worked at about 16 photographs per second. This reduced the jerkiness very much, and in December 1895 the Lumiere brothers gave the worlds's first real cinematograph show. Their film was called The Arrival of a Train at a Station. The film was so good that some of the audience almost expected the train to rush out at them from the screen. In 1903 one of Edison's cameramen made a new long picture. It was called «The Life of an American Fireman». People liked it and asked for more; and so more films of this kind were made. More cinemas were built.
These first films had no sound. When it was necessary, printed words were thrown on the screen to explain what was happening or what people were saying. Usually music was played during the showing of a film. If the film was showing moonlight on the sea, the music was gentle and sweet. If there was a fight or a storm, the music wasloud and noisy.-
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Автор:
cassiedioz - 5 лет назад
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