IRON GROUP IN PRESENCE OF PHOSPHORIC Manganese, Zinc, Chromium, Barium, Strontium, aad MagTo the filtrate from the sulphides of the Cu and As groups add (N H4) HG (till some time and filter. Wash well with water containing (NH4)2 S, and finally RESIDUE. METHOD I. Cr Is ABSENT. Boil down with a few drops of H NO3 (yellow coloration indicates the presence of Iron). again and filter. Residue. Add dilute H2 SO4, bou FILTRATE. ACID, &c. Separation of Iron, Nickel, Cooalt, Alumínium, nesium, in presence of Phosphoric, Boric, and Oxalic Acids. alkaline), N H4 Cl and (N H4)2 S Warm the mixture gently in a flask, shake for once with water alone. Treat the precipitate with cold dilute H Cl, and filter. FILTRATE. Cr,Al,Fe, Zn, Mn, Ca,Ba,Sr, Mg,H3P04,H3BO3 and H2C204 Test small portions for Cr, Fe, H3 P O4, H3 BO3 and H2 C2 04. Adopt Method I. if Cr be absent; Method II. if present. METHOD II. Cr IS PRESENT. Boil down with a little K Cl 03 till it smells of chlorine. Test for Ba, Sr, and Ca in a portion of the solution, as in 1. To the remainder add Fe, Cl, as in I : evaporate down nearly to dryness, dilute with water, add Na, CO3, or K H O, til! just neutral or slightly acid, when perfectly cold, add Ba CỖ3 in slight excess, place in a small flask, close with a cork, shake well, and allow to settle. Filter. APPENDIX D. TREATMENT OF PLATINUM RESIDUES. THESE residues generally contain the platinum as double chloride of potassium or ammonium. Any soluble platinum chloride is precipitated by addition of ammonium chloride, and the filtered precipitate is dried and ignited. The residue is then thoroughly washed with hot water, and dissolved by boiling with a mixture of three parts of hydrochloric to one of nitric acid. It is best to pour off the solution from time to time and add fresh acids. When all the platinum is dissolved the solution is evaporated nearly to dryness; hydrochloric acid is added (to expel the nitric acid), and the liquid is evaporated to complete dryness on the water bath. The residue is dissolved in water or preserved dry in bottles. QUESTIONS AND EXERCISES. 3. (a) How many grams of oxygen can be obtained by heating 1,080 grams of mercuric oxide ? ४० (6) Twenty-four grams of oxygen are required; how much mercuric oxide must be heated? 324 4. (a) What is left when potassium chlorate is heated? катоз (6) How many grams of potassium chlorate must be heated in order to yield 500 grams oxygen? (c) How much potassium chloride will remain after heating 247 grams potassium chlorate ? 5. How is potassium chlorate distinguished from potassium chloride? 6. (a) Describe the best means of preparing oxygen? (b) The residue in a flask used to prepare oxygen, consisted of 13 grams of potassium chloride; how much chlorate had been heated, and how much oxygen evolved? (c) Why is manganese dioxide mixed with potassium chlorate in preparing oxygen? 8. (a) What happens when a taper is burned in oxygen? (b) How is the presence of carbon dioxide generally ascertained? 9. (a) 14 gram of charcoal containing 96 per cent. of carbon is burnt in oxygen; how much carbon dioxide is produced? (b) Contrast the burning of a candle with the breathing of an animal in air. 10. How much oxygen is required to burn 42 grams of sulphur to sulphur dioxide? 11. How much phosphoric anhydride can be obtained by burning 2*34 grams phosphorus in oxygen, and how much phosphoric acid would be obtained by dissolving the anhydride in water? 13. (a) How much hydrogen can be got by dissolving 15 ounces of zinc in sulphuric acid? (b) Which will yield the greater quantity of hydrogen when dissolved in acids-162 grams zinc, or 140 grams iron? Why? 14. How much water will be formed by burning all the hydrogen evolved by dissolving 3'42 grams zinc in sulphuric acid? 15. How much zinc sulphate should be got by dissolving I lb. zinc in sulphuric acid? 19. How is nitrogen prepared? 21. One hundred grams of potassium nitrate are heated with sulphuric acid; how much nitric acid and hydrogen potassium sulphate will be obtained? 22. What are the best tests for nitric acid? |