ACIDS 147 



red. Its action on chalk and lime is similar to that with hydrochloric 

 acid. Its action on most metals is violent, a red gas being given off. 

 With copper a blue solution is left, or green if excess of acid is used. It 

 is to be noted that none of the metals caused an inflammable gas to 

 be given off with nitric acid. 



QUESTIONS ON CHAPTER XXIII. 



114. What are the chief characteristics of acids ? Describe how you 

 would prepare nitric acid. 



115. Being given an acid, which is either hydrochloric, nitric or sulphuric, 

 how would you determine which it is ? 



116. Tabulate the effects of acting on copper and zinc with the three 

 common laboratory acids, dilute and strong (with heat if no effect is produced 

 in the cold). Tabulate also the properties of not more than two of the 

 gaseous products. 



117. Sketch the apparatus you would employ if you wished to fill a 

 flask with dry hydrochloric acid gas, and describe briefly how you would 

 conduct the experiment. How would you show experimentally that the 

 gas contains hydrogen ? 



118. Weighed quantities of water and concentrated sulphuric acid are 

 placed, side by side, in an enclosed volume of air and allowed to remain there 

 for several days. What changes would you find on examination at the end 

 of that period ? What conclusions would you draw from the results 

 observed ? Mention some other substances which would afford similar 

 results. 



119. Set down in tabular form observations you have made in the labora- 

 tory which would enable you to distinguish between the metals lead, zinc, 

 copper, tin, iron, by using dilute and concentrated hydrochloric acid, cold 

 and hot. 



120. Describe the action of dilute and strong nitric acid on copper, zinc 

 and iron. Tabulate your results. 



