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CYANOGEN AND ITS COMPOUNDS.

1116. What occurs when nitrogen is passed over a strongly heated mixture of charcoal and potassium carbonate? Give an equation.

1117. How is cyanogen gas prepared, and how may it be liquefied? What is its action on potassium ?

1118. Starting with cyanogen how may oxalic acid be obtained, and vice versa. Show by formulæ how the two substances are related to each other.

1119. What products are obtained when cyanogen gas burns in air? Give the volumes of each obtained by burning 15 litres of the gas.

1120. Give the weight and volume of cyanogen which should be obtained by decomposing 79 granımes ammonium oxalate with phosphoric anhydride.

1121. What is paracyanogen, and how is it obtained ?

1122. What organic compound is formed when sulphuretted hydrogen acts on mercuric cyanide ? Give other methods for preparing the same substance.

1123. What is the action of strong and of dilute sulphuric acid on potassium ferrocyanide ? Give equations for each reaction.

1124. How would you act on chloroform so as to obtain hydrocyanic acid ?

1125. What changes occur when an aqueous solution of hydrocyanic acid is left standing for some time?

1126. How is potassium cyanide made (a) from hydrocyanic acid, (6) on the large scale? What occurs when it is heated in contact with air ?

1127. How is hydrocyanic acid detected in cases of poisoning? How may it be detected in a compound n soluble in water and not decomposed by acids ?

1128. Give different methods for the preparation of potassium ferro- and ferricyanide.

1129. How could you obtain from potassium ferrocyanide (a) potassium cyanide, (6) hydroferrocyanic acid, (c) Prussian blue?

1130. What is Turnbull's blue, and how is it made ?

1131. Give a short account of the nitroprussides and sulphocyanides.

N

METHYL COMPOUNDS.

1132. How does marsh-gas occur in nature ? By what other names is the substance known ? Give four distinct methods for its preparation.

1133. What are the products of the action of chlorine on marsh-gas?

1134. Nine litres of marsh-gas are mixed with nine of chlorine and exposed to light. Give the volumes and weights of the products.

1135. What weight of sodium acetate when heated with caustic soda is needed to yield 275 C.C. of marsh-gas at N.T.P. ?

1136. One hundred and eighty-nine c.c. of marsh-gas are completely burned in air. Find the volume of air required and of the products of combustion at N.T.P.

1137. What volume of oxygen must be exploded with 150 C.C. of marsh-gas so as to ensure complete combustion ?

1138. What volume of marsh-gas at N.T.P. when passed over heated copper oxide should yield 10 grammes of carbon dioxide ?

1139. Give two methods for the preparation of methyl chloride. What is the action of potash on it?

1140. How is chloroform prepared on the large scale ? What is the action of nascent hydrogen, and of chlorine

on it ?

1141. What products are obtained by the destructive distillation of wood, and how is the wood spirit separated from them, and obtained pure ?

1142. How is methyl alcohol obtained from (a) methyl chloride, (6) gaultheria oil ? What is the action of potassium on methyl alcohol ?

1143. What volume of oxygen is required for the complete combustion of 7 grammes of methyl alcohol?

1144. What two compounds have the empirical formula C,H,N? How is each prepared, and what is the constitutional formula for each ? From which, and how, could an ethyl compound be obtained ?

ETHYL COMPOUNDS,

1145. Give several reactions for preparing ethyl hydride. How has it been proved identical with dimethyl ?

1146. What is the action of chlorine on ethyl hydride ?

1147. How is ethyl chloride prepared (a) by Grove's method, (6) by other methods ? What is the action of potash on it?

1148. How is ethyl iodide prepared ? What weight of it contains 7.89 grammes of iodine ?

1149. How is ethyl alcohol obtained from grape sugar ? What other products are simultaneously produced ?

1150. What is absolute alcohol, and how is it prepared ?

1151. How is the amount of alcohol in a mixture of alcohol and water accurately ascertained ?

1152. What is the action on alcohol of each of the following bodies ? (a) sodium, (6) chlorine, (c) sulphuric acid, (d) a mixture of sulphuric acid and potassium bichromate. Give equations for the reactions.

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