permanganate solution until a pink color is obtained which persists for 15-20 seconds. From the molarity of the permanganate solution and the fact that the antimony is oxidized from the trivalent to the pentavalent state, calculate the amount of Sb present in the sample; also calculate the corresponding amount of Sb2O4 and apply the necessary correction for Sb2O4 in the impure stannic oxide, § 410. Note 1. Hot 18 molar sulphuric acid oxidizes metallic antimony to antimonous ion, provided the heating is not carried on after all the antimony is in solution; the tin is oxidized to stannic ion, while the lead separates out as lead sulphate. Note 2. The potassium sulphate is added in order to raise the boiling point of the solution and thereby bring about a more rapid decomposition of the alloy. Note 3. The addition of the tartaric and hydrochloric acids serves to keep the antimony in solution by forming the complex tartrate ion and by preventing the hydrolysis of the antimony salts. Note 4. The solution is titrated at once, because upon standing some antimonous ion is oxidized by atmospheric oxygen. Note 5. The solution must be cooled to room temperature before titrating because chloride ion is rapidly oxidized to chlorine by permanganate ion in hot solutions. Note 6. The end point is not permanent but gradually fades due to the slow oxidation of chloride ion to chlorine by the slight excess of permanganate ion necessary to give the end point. Saturated Solutions of Some Reagents Table of Percentages of Ionization of Acids Table of Percentages of Ionization of Bases Tables of Units of Mass. Tables of Units of Liquid Capacity Tables of Units of Dry Capacity Tables of Units of Length Tables of Units of Area . Tables of Units of Volume Tables of Units of Wire Measure 1 Compiled by the International Committee on Atomic Weights, consisting of F. W. Aston, Gregory P. Baxter, Bohuslav Brauner, A. Debierne, A. Leduc, T. W. Richards, Frederick Soddy and G. Urbain J. A. C. S. 47, 600 (1925). 120 918 954 121 122 123 124 447 482 517 990 *027*063*099 *135*171*207 *243 38 37 36 955 *307 552 656 123456789 4 2 8 747 4 7 11 15 15 23 9 34 11 14 19 19 18 22 27 26 25 30 30 29 33 32 066 098 130 162 194 322 123456789 1 4 3 7 7 7 11 10 10 14 14 18 17 17 21 20 20 25 24 28 27 26 32 31 30 140 141 142 143 144 613 644 675 706 737 768 799 922 953 983 *014 *045 *076*106 15 229 259 290 320 351 381 412 534 564 594 625 655 685 715 836 866 897 927 957 987 *017 829 860 891 *137*168 *198 442 473 32 31 503 145 146 147 148 149 16 137 167 197 227 256 286 316 376 406 * This table has been verified by comparison with the values given in the following publication, A New Manual of Logarithms to Seven Places, edited by Dr. C. Bruhns, Bernhard Tauchnitz, Leipzig, 1913; Lemcke & Buechner, New York, 11th stereotype edition. |