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1101. In the analysis of a silver salt the following results were obtained by Frankland :

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(a). Substance taken

0 4108 gramme.
Carbon dioxide obtained = 0'2133
Water obtained

0'0653

also (6). 0-36 gramme yielded on ignition o‘232 gramme

silver. Find the percentage composition and formula of the salt.

1102. What weight of silver chloride should be obtained in the analysis of 0-7899 gramme of chloral ?

1103. Why is it important to ascertain if possible the vapour density of an organic body?

1104. Describe the methods for ascertaining vapour density introduced by (a) Dumas, (6) Gay-Lussac, (c) Hofmann,

1105. Find the vapour density of an organic compound from the following data :

Grammes. 44"7832 45'1848

Weight of globe filled with dry air

vapour at 115o C. Capacity of globe = 189:6 c.c. Temperature = 12:8° C. Barometer

751 m.m.

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1106. In a determination of the vapour density of boric ethide, Frankland obtained the following results :-

Weight of boric ethide . O‘2839 gramme.
Volume of vapour

96-68 c.c.
Temperature of oil bath 149° C.
Barometer.

760-5 m.m.
Height of mercury inside the
tube above that outside

15 m.m.
Height of column of oil 328.0 m.m.

Calculate the density of the vapour. 1107. Describe fully all the methods used for ascertaining the molecular formulæ of organic bodies.

1108. By whom and when was the synthesis of an organic compound first made ? Describe fully the method employed.

1109. Give a historical sketch of the introduction of synthesis in organic chemistry.

1110. How may alcohol be built up from inorganic materials ?

11. What are empirical, rational, constitutional, and graphic formulæ ? Give examples.

1112. Explain the terms isomerism, metamerism, and polymerism, and illustrate your meaning by examples.

1113. Explain the use in organic chemistry of the process called fractional distillation.

1114. Give examples of positive and negative organic and inorganic radicals.

1115. Give constitutional and graphic formulæ for the following organic bodies : (a) alcohol, (6) marsh gas, (c) hydrocyanic acid, (d) ether, (e) oxalic acid, (f) aldehyde, (8) acetic ether, (h) formic acid, (i) urea, (j) succinic, acid, (k) acetic acid, (1) benzol, (m) benzoic acid.

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, (b) 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.

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