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1919 



Comprehensive Examination 

 CHEMISTRY 



Wednesday, June 18 2-5 p.m. 



Answer ten questions as indicated below. 



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



Part I 

 (Answer all questions in Part I.) 



1. Define and give an example of (a) catalysis, (b) equivalent of an element, 



(c) allotropy, (d) molecular weight, (e) carbohydrate. 



2. Write equations for the following reactions, using formulas throughout. The 



equations must be properly balanced to receive credit. 



a) Sodium chloride+ manganese dioxide+concentrated sulphuric acid= 



b) Ferric chloride^- calcium hydroxide = 



c) Lead nitrate+ hydrogen sulphide (solutions) = 



d) Ammonium sulphate+ sodium hydroxide = 



e) Concentrated nitric acid heated = 



3. a) How many cubic centimeters of oxygen, measured at 0° C. and 760 mm. 



can be obtained by the complete decomposition of one kilogram of 

 3 per cent solution of hydrogen peroxide, H2Qj, into water and oxygen ? 

 (H 1, O 16.) 



Note. — A liter of oxygen at 0° and 760 mm. weighs 1.43 grams. 



b) What is the percentage of silica, Si02, in the mineral analcite, 



NaaSiOs- Al2(Si03)3-2H20 ? (Si 28, Al 27, Na 23, O 16, H 1.) 



4. Explain each of the following experimental facts: 



c) A dilute solution of potassium chloride has a lower freezing-point than one 



of sugar of the same concentration measured in gram molecules per 

 liter. 



b) A drop of concentrated sulphuric acid on a wooden table makes a black 



spot. 



c) Many minute gas bubbles appear on the inside of a glass of cold water 



standing in a warm room. 



d) Copper does not Hberate hydrogen from nitric acid. 



e) Concentrated hydrochloric acid, if added to a saturated solution of sodium 



chloride, gives a white precipitate. 



(THIS EXAMINATION IS CONTINUED OR PAGE 2) 



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