I9i6 



Comprehensive Examination 



CHEMISTRY 



Monday, September i8 2:00-5:00 p.m. 



A teacher's certificate covering the laboratory instruction must be presented as a 

 part of the examination unless the laboratory notebook is to be presented at a laboratory 

 examination. 



Answer ten questions as indicated below. 



Attach to the answer, in each case, the number and letter used in the printed paper. 



Part I 

 (Answer all questions in Part I.) 



1. a) Define the terms "molecule," "atom," and "ion." 



b) State Avogadro's h>T)othesis, and show how it guides the chemist in 

 determining molecular weights. 



2. a) What takes place when steam is passed over heated zinc or iron ? 



b) How would you identify the products ? 



c) What do you learn about the composition of water from this experiment ? 



3. Describe the action, if any, and represent by equations the chemical changes 



taking place when dilute hydrochloric acid and nitric acid are added 

 separately to each of the following substances: (a) ferric hydroxide, (b) zinc 

 oxide, (c) calcium carbonate, (d) silver. 



4. a) Calculate the percentage of oxygen in crystalHzed copper nitrate, 



Cu(N03).-6H,0. (Cu = 64, N=i4, = i6, H=i.) 

 b) What weight, and volume at 0° C. and 760 mm., of carbon dioxide can 

 be obtained by treating an excess of sodium acid carbonate with 490 gm. 

 of sulphuric acid containing 20 per cent of H^SO^ ? (Na = 23, C = 12, 

 0=16, H=i, S = 32.) 

 Note. — A liter of carbon dioxide at o°C. and 760 mm. weighs i .97 gm. 



5. Define and illustrate with an example each of the following: (a) acid 



anhydride, (b) catalytic agent, (c) saturated solution, (d) subHmation, 

 (e) either destructive distillation or fractional distillation. 



Part II 

 SUPPLEMENTARY REQUIREMENTS 

 ' Group A 



(Answer two questions from this group.) 



6. Two rods of copper are placed in a solution of copper sulphate. What takes 



place when a current of electricity is passed from one rod to the other 

 through the solution? How might you prove what happens to each of 

 the copper rods ? 



(SEE NEXT PAGE) 

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