Elements of Inorganic Chemistry, Descriptive and Qualitative

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268

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395 g

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Cambridge Scholars Publishing

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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER I. OXYGEN: ITS OCCURRENCE, PREPARATION, PROPERTIES, AND TESTS. OZONE. THE ELEMENT OXYGEN. Symbol O." ? Atomic Weight, 16; Specific Gravity, 1.1056. 26. Occurrence. ? Oxygen occurs well-nigh everywhere in nature. It constitutes 44 to 48 per cent of the weight of the earth's crust, 88.89 per cent of water, and about 23 per cent of the atmosphere. Oxygen occurs in combination with every known element except fluorine. 27. Preparation. ? Exp. 5 p. Heat one gram mercuric oxide, HgO, in a hard glass test-tube. The oxygen is driven off, while the mercury is condensed on the sides of the tube. Test the presence of the gas with a glowing match. (HgO = Hg + 0.) Query. Aug. 1, 1774, Joseph Priestley made this experiment for the first time. What gas did he discover ? Exp. 6 p. Minium, or red oxide of lead, Pb3O4, is to be heated as above. A part of the oxygen is driven from the red oxide of lead with great difficulty. (Pb3O4 = 3 PbO + 0.) Test as before. Suo. Try KCl03 with and without Mn02, as above. Also heat, as ahove, KCl03 with a pine splinter. What occurs ? Explain. Queries. Why docs not the red oxide of lead, Pb304, part with its oxygen as readily as mercuric oxide, HgO ? Aim. The lead has a stronger chemism for oxygen than mercury has. It is upon the principle of variable degrees of chemism existing between different substances, that double chemical reactions are always based. Do you obtain metallic lead in this experiment 1 Heat some red oxide of lead on charcoal, with sodium carbonate (Na2C03), before the blow-pipe. Do you now obtain metallic lead ? What effect do the sodium carbonate and charcoal have on substances treated thus ? Ans. The charcoal abstracts oxygen from the oxicje, or acts as a strong reducing age.nt. The sodium carbonate serve...

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Mehr von:  James Henry Shepard, Cambridge Scholars Publishing