. The principles of chemistry . acid, but such asimple representation, which we shall cite afterwards, hides the mechanism of the reaction,and does not permit of its actual complexity being seen. ^^ According to Thomsen the reaction between zinc and a very weak solution ofsulphuric acid evolves about 3H,000 calories (zinc sulphate being formed) per G5 parts THE COMPOSITION OF WATER, HYDROGEN 125 sulphuric acid is replaced by a metal, a substance is obtained which iscalled a salt of sulphuric acid or a sulphate. Thus, by the action of zincon sulphuric acid, hydrogen and zinc sulphate ZnS04,^-^b
. The principles of chemistry . acid, but such asimple representation, which we shall cite afterwards, hides the mechanism of the reaction,and does not permit of its actual complexity being seen. ^^ According to Thomsen the reaction between zinc and a very weak solution ofsulphuric acid evolves about 3H,000 calories (zinc sulphate being formed) per G5 parts THE COMPOSITION OF WATER, HYDROGEN 125 sulphuric acid is replaced by a metal, a substance is obtained which iscalled a salt of sulphuric acid or a sulphate. Thus, by the action of zincon sulphuric acid, hydrogen and zinc sulphate ZnS04,^-^bis are latter is a solid substance, soluble in water. In order that theaction of the metal on the acid should go on regularly, and to tlie end,it is necessary that the acid should be diluted with water, which dis-solves the salt as it is formed ; otherwise the salt covers the metal,and hinders, the acid from attacking it. Usually the acid is dilutedwith from three to five times its volume of water, and the metal is. Fig. 20.—Apparatus for the preparation of hydrogen from zinc and sulphuric acid. covered with this solution. In order that the metal should actrapidly on the acid, it should present a large surface, so that a maxi-mum amount of the reacting substances may come into contact in agiven time. For this purpose the zinc is used as strips of sheet zinc,or in the granulated form (that is, zinc which has been poured from acertain height, in a molten state, into water). The iron should be inthe form of wire, nails, filings, or cuttings. by weight of zinc; and 56 parts by weight of iron—which combine, hke 65 parts byweight of zinc, with 16 parts by weight of oxygen—evolve about 25,000 calories (forninigferrous sulphate, FeSOj). Paracelsus observed the action of metals on acids in theseventeenth century ; but it was not until the eighteenth century that Lemery determmedthat the gas which is evolved in this action is a particular one which differs from airand
Size: 2198px × 1137px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublis, booksubjectchemistry
