!Answer!: 0.4667 gram.
43. One tenth gram of iron wire, 99.78% pure, is dissolved in hydrochloric acid and the iron oxidized completely with bromine water. How many grams of stannous chloride are there in a liter of solution if it requires 9.47 cc. to just reduce the iron in the above? What is the normal value of the stannous chloride solution as a reducing agent?
!Answer!: 17.92 grams; 0.1888 N.
44. One gram of an oxide of iron is fused with potassium acid sulphate and the fusion dissolved in acid. The iron is reduced with stannous chloride, mercuric chloride is added, and the iron titrated with a normal K_{2}Cr_{2}O_{7} solution. 12.94 cc. were used. What is the formula of the oxide, FeO, Fe_{2}O_{3}, or Fe_{3}O_{4}?
!Answer!: Fe_{3}O_{4}.
45. If an element has 98 for its atomic weight, and after reduction with stannous chloride could be oxidized by bichromate to a state corresponding to an XO_{4}^{-} anion, compute the oxide, or valence, corresponding to the reduced state from the following data: 0.3266 gram of the pure element, after being dissolved, was reduced with stannous chloride and oxidized by 40 cc. of K_{2}Cr_{2}O_{7}, of which one cc. = 0.1960 gram of FeSO_{4}(NH_{4}){2}SO{4}.6H_{2}O.
!Answer!: Monovalent.
46. Determine the percentage of iron in a sample of limonite from the following data: Sample = 0.5000 gram. KMnO_{4} used = 50 cc. 1 cc. KMnO_{4} = 0.005317 gram Fe. FeSO_{4} used = 6 cc. 1 cc. FeSO_{4} = 0.009200 gram FeO.
!Answer!: 44.60%.
47. If 1 gram of a silicate yields 0.5000 gram of Fe_{2}O_{3} and Al_{2}O_{3} and the iron present requires 25 cc. of 0.2 N KMnO_{4}, calculate the percentage of FeO and Al_{2}O_{3} in the sample.