QUESTIONS AND PROBLEMS 125 



106. What is the relative density of ammonia, and how is it determined ? 



107. What is the composition of sal-ammoniac, and how may it be 



determined synthetically ? 



108. What is meant by the term " ammonium," and why is it employed ? 



109. How may ammonium salts be recognised ? 



1 10. Prepare a bottle full of ammonia gas. 



111. Determine the strength of the solution of ammonia. 



112. Identify the salts. (Ammonium chloride and barium chloride.) 



Nitric Acid and the Nitrates. 



113. What are saltpetre and Chili saltpetre, and how are they dis- 



tinguished ? 



114. Wliat evidence is there that nitric acid is an oxygenated acid? 



Give the formulae for nitric acid and nitric anhydride. 



115. A solution containing i gram of potash (KgO) when exactly 



neutralised with a solution of nitric acid and evaporated, leaves a 

 residue weighing 2. 149 grams. What formula will represent the 

 composition of the salt ? W^hat reasons are there for supposing 

 that sodium nitrate would have an analogous composition ? 



116. How may nitric acid be prepared? Explain the occurrence of red 



fumes during the process. 



117. For what reason is nitric acid spoken of as a powerful oxidising 



agent ? Illustrate your answer by examples. 



118. What is an explosive? Illustrate your answer by the composition 



and action of gunpowder. 



119. Fully describe the action of nitric acid upon metals. Explain the 



difference in the gaseous products, depending upon the strength 

 of the acid employed ; also the difference in the soUd product of 

 the action of tin from that of the action of copper on nitric acid. 



120. Name the three gaseous oxides of nitrogen, express their composition 



by formulae, and state how they may be distinguished from each 

 other and from nitrogen. 



121. What is nitrous acid, and how may it be produced? What is the 



anhydride of nitrous acid, and into what two oxides of nitrogen 

 should this unstable anhydride be decomposed when warmed ? 



122. How may nitrogen gas be prepared from a mixture of solutions of 



sodium nitrite and sal-ammoniac? Explain the reaction, and 

 state why, when once the temperature is reached at which it 

 begins, no further heating is necessary. 



123. What is the density of nitrogen gas compared with hydrogen as 



unity, and how may it be determined ? 



