Imágenes de páginas
PDF
EPUB

PLATINUM,

1048. How does platinum occur in nature, and how is the metal prepared (a) by Wollaston's process, (6) by the process of Deville and Debray ?

1049. Describe the apparatus of Deville and Debray for fusing platinum.

1050. Why are platinum vessels frequently employed by chemists ? Name substances which attack platinum.

1051. What are platinum black and spongy platinum ? How are they each prepared, and how do they differ from ordinary platinum ?

1052. How is platinum tetrachloride prepared, and how may the metal be obtained from it?

1053. Express by equations the action of ammonium chloride on platinum chloride, and of heat on the product.

1054. What is the action (if any) of each of the following bodies when heated with platinum ? (a) potash, (6) silica, (c) nitric acid, (d) carbon, (e) lead, (f) sodium carbonate, (g) phosphorus, (h) chlorine, (i) sulphur, (j) potassium bisulphate.

M

LEAD.

1055. What is the composition of the following lead compounds ? (a) massicot, (6) galena, (c) litharge, (d) cerussite, (e) red lead, (f) pyromorphite, (g) anglesite.

1056. Describe methods for the assay of lead ores, and also for estimating the quantity of silver in argentiferous galena.

1057. How does lead sulphide itself serve for the reduction of the ore, without the addition of reducing agents ? Give equations.

1058. Describe the processes for lead-smelting in (a) reverberatory furnaces, (6) in blast-furnaces, (c) in shallow hearths.

1059. What is "lead fume," and what arrangements are made to collect it?

1060. Describe fully Pattinson's process for the desilverisation of lead; also the subsequent process of cupellation to obtain the silver.

1061. How are lead pipes and sheet-lead made? 1062. What is the action of water on lead ? Whether does rain, river, or distilled water act most on lead, and what is the reason ?

1063. How may lead be obtained chemically pure ? Describe methods for obtaining metallic lead in crystals.

1064. What is the action of each of the common acids on lead ? Describe the nitrate, chloride, and sulphate of lead.

1065. Describe the oxides of lead, and give methods for their preparation.

1066. How is lead tetrachloride prepared, and what occurs when it is added to water ?

1067. Describe the manufacture of acetate of lead and of white-lead. What is the composition of whitelead ?

1068. What is the action of nitric acid on red-lead and on galena?

PENTAD.

VANADIUM.

1069. Give a short account of the occurrence of vanadium in nature, and state how the metal is obtained.

1070. How was the combining weight of vanadium ascertained by Roscoe? How did his results differ from those of Berzelius ?

1071. Write the formulæ of the oxides, oxychlorides and chlorides, of vanadium (a) as given by Berzelius, (6) as given by Roscoe.

1072. How is vanadium pentoxide obtained, and what are its properties? What occurs when its solution in sulphuric acid is treated with zinc ?

1073. Find the combining weight of vanadium from the following results : (a) 6'139 grammes vanadium pentoxide when heated in hydrogen yielded 5'0639 grammes trioxide, (ö) vanadyl trichloride contains 61'276 per cent. of chlorine.

1074. Compare the compounds of vanadium with those of phosphorus, and point out their analogies,

HEXADS.

MOLYBDENUM, ETC.

1075. What compound of molybdenum results from heating the sulphide in a current of air, and what is the action of ammonia on it?

1076. What is the action of ammonium molybdate on solutions of phosphates ? Mention other substances precipitated by the same salt.

1077. How is tungstic acid obtained from sodium tungstate, and how is this salt prepared ?

1078. How is tungsten hexachloride prepared ? Give the formulæ of all the compounds of tungsten with chlorine, and with chlorine and oxygen.

1079. Name the chief minerals in which molybdenum, tungsten, and uranium occur.

1080. Point out analogies existing between molybdenum, tungsten, and uranium, and also between the last element and vanadium.

1081. Give reactions for distinguishing all the metals mentioned in the previous question.

« AnteriorContinuar »