Applied Chemistry Volume 1 ; Water, detergents, textiles, fuels, etc

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. 1920 Excerpt: ...concentrated solutions, but tends to decompose in the presence of small quantities of impurities, such as are usually found in commercial preparations. Determination of the Amount of Hydrogen Peroxide or of "Available Oxygen" in a Solution of Hydrogen Peroxide. The amount of hydrogen peroxide, or of "available oxygen," in a solution of hydrogen peroxide, can be determined by several different methods:--I. By Determining the Amount of Iodine Liberated from an Acidified Solution of Potassium Iodide.--Hydrogen peroxide, like other oxidising agents, liberates iodine from an acidified solution of potassium iodide, and if considerable excess of sulphuric acid is present, the reaction may be made use of quantitatively. H202 + 2HI-2H20 + I2 34 2 x 127 17 127 The iodine thus liberated can be titrated with decinormal sodium thiosulphate solution, as described under "bleaching powder" (seep. 137). The above equation shows that 17 parts H2O2 liberate 127 parts iodine, and since 1 c.c. N/10 sodium thiosulphate = 0-0127 gm. iodine,.-. 1 c.c. N/10 sodium thiosulphate = 00017 gm. H202. Or, since 17 parts H202 give 8 parts "available oxygen," 1 c.c. of N/10 thiosulphate = 0-0008 gm. "available oxygen ". If the strength of an approximately 10 volume solution of hydrogen peroxide is required, dilute the solution 1 in 5, and to 10 c.c. of the diluted solution add 10 c.c. of a 10 per cent. solution of potassium iodide and 30 c.c. of dilute sulphuric acid. After standing for a few minutes, titrate the liberated iodine with decinormal thiosulphate (see p. 137). II. By Measuring the Volume of Oxvgen Liberated on Treating with. an Acidified Solution of Potassium Permanganate.--Hydrogen peroxide and potassium permanganate are both 1o...