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. 1921 Excerpt: ...water and shake well. Preserve in a well-stoppered bottle in a cool, dark cupboard. (b)--Thiosulphate, NaOs, 5H2O =248'2.--Thiosulphate cannot generally be obtained chemically pure. Hence weigh out roughly 28-29 gms., dissolve in cold freshly-boiled distilled water in the 1100 c.c. Giles flask, and titrate N...... ...
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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. 1921 Excerpt: ...water and shake well. Preserve in a well-stoppered bottle in a cool, dark cupboard. (b)--Thiosulphate, NaOs, 5H2O =248'2.--Thiosulphate cannot generally be obtained chemically pure. Hence weigh out roughly 28-29 gms., dissolve in cold freshly-boiled distilled water in the 1100 c.c. Giles flask, and titrate N...... against the--iodine, using starch solution as indicator. (Do not add the starch solution till the colour of the iodine is pale straw-colour.) Calculate N and dilute to--as usual. Preserve in the dark in well-stoppered bottles. Iodine solution prepared and kept as above keeps well, but the thiosulphate should be frequently re-titrated. N. 1 c.c.--thiosulphate =-012692 gm. iodine. (c) Preparation of the starch solution.--About a gram of the best potato starch is made into a thin cream with a few c.cs. of water and poured into 100 c.cs. of boiling water. Filter and use at once. About 5 c.cs. should be used for each titration. It is more convenient to use one of the forms of " soluble starch " which are now on the market. Other Methods of standardising thiosulphate. The methods now to be described are exceedingly accurate, and if desired it is well to standardise the thiosulphate thus and to use it to standardise the iodine. N N 2. By--K2Cr2O7 or KMnO4.--25 c.cs. of--K2Cr207 or KMn04 are run into about 25 c.cs. of 5 % potassium iodide solution, and acidified strongly with acetic or dilute hydrochloric acid. An amount of iodine is thus liberated N. corresponding to 25 c.cs. of--iodine. Titrate with the thiosulphate, adding starch solution towards the end of the reaction. Remember that the solution, when dichromate is used, will be green at the finish., 3. By r--potassium bi-iodate.--This salt is readily obtained in a high state of purity. On ...
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Add this copy of A Text-Book of Practical Chemistry to cart. $24.01, new condition, Sold by Ingram Customer Returns Center rated 5.0 out of 5 stars, ships from NV, USA, published 2022 by Legare Street Press.
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