1917 

 CHEMISTRY 



Friday 2 p.m. Two hours 



Answer nine questions as indicated below. No extra credit will be given for more 

 than nine questions. 



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



Part I 

 (Answer all questions in this group. Each question counts 12.) 



1. Write equations for the following reactions, using formulas throughout. To 



receive credit, the equations must be absolutely correct. 



(a) Sodium acid carbonate+sulphuric acid = 



ijb) Carbon dioxide + heated carbon = 



(c) Silver sulphate + barium chloride = 



{d) Copper+hot concentrated sulphuric acid= 



(e) Hydrogen sulphide burned in excess of air = 



(/) Potassium chlorate heated with manganese dioxide = 



2. Select three of the substances: chlorine, potassium nitrate, zinc, slaked lime, 



and give the following information in regard to each: (a) Name a naturally 

 occurring material from which the substance is commonly made, {b) 

 Write the equation or equations representing the preparation of the sub- 

 stance from this material, (c) Give one important commercial use. 



3. (a) Given a soluble oxide, how could you determine whether or not it was 



the oxide of a metal ? 

 iJb) What three tests could you make to distinguish between sodium 



chloride and finely divided parafl&n ? 

 (c) Define the term "radical," and illustrate by an example. 

 {d) Illustrate the law of multiple proportions by considering the composition 



by weight of two compounds containing the same elements. 



4. (a) What forms of energy are manifest when a mixture of hydrogen and 



oxygen is exploded? From what source are these forms of energy 

 derived ? Apply the law of conservation of energy to this reaction. 

 {b) Excess of phosphorus is allowed to act on air at atmospheric pressure in a 

 sealed flask. When the reaction is complete, (1) What is the pressure 

 (approximately) in the flask, the temperature remaining the same? 

 (2) How does the weight of the flask and contents after the reaction 

 compare with the weight before ? State the law upon which the latter 

 conclusion is based. 



5. (a) If 50 .0 grams of calcium carbonate, CaCOs, are added to 50.0 grams of 



hydrochloric acid, HCl, in water solution; which substance remains 

 in excess? What is the weight of this excess? (Atomic weights: 

 Ca 40, CI 35.5, O 16, C12, H 1.) 



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