Laboratory manual and principles of chemistry for beginners

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt: ... the same regardless of the chemical changes that take place. This fact renders it possible to express chemical changes in the form of an equation. All the substances taking part in a given chemical change are written in the first member of the equation, and all the substances resulting from the change are written in the second member of the equation; each substance being separated from the others by the sign of addition ( + ), and the two sides of the equation connected by the sign of equality (= ). The total amount of each element and the total amount of material must be the same on the two sides of the equation. A very simple equation is that representing the decomposition of water by electricity shown in Exp. 26. H20 = 2H + 0. (1) The formation of water from its elements, as in Exp. 25, would be expressed by the equation 2H + 0 = H20. (2) The formation of oxygen from potassium chlorate, as in Exp. 29, would be expressed KCl03=KCl + 30. (3) The substance remaining behind after the oxygen is driven off is called potassium chloride, and has the formula KCl. The formation of hydrochloric acid, HCl, from sodium chloride, NaCl (common salt), and sulphuric acid, H2S04 (see Exp. 61), is represented by the equation 2 NaCl + H2S04 = 2 HCl + Na2SCv (4) Again, the formation of chlorine from sodium chloride, NaCl, sulphuric acid, H2S04, and manganese dioxide, Mn02, as in Exp. 68, may be expressed by the equation 2 NaCl + Mn02 + 2 H2S04 = Na2S04 + MnS04+2Cl+2H20. (5) These equations are short and concise ways of expressing chemical facts: Equation (1) expresses the fact that water is decomposed, yielding hydrogen and oxygen. Equation (2) expresses the fact that hydrogen and oxygen unite to form water. Equation (3) expresses the fact that potassium chlorate is broken ...