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Part II 

 (Answer five questions frotn Fart II. Extra questions will receive no credit.) 



6. A liter of a certain elementary gas weighs 7.50 grams, while a liter of hydrogen 



gas under the same conditions weighs 0.050 gram. The atomic weight 

 of the element composing the gas is 75. How many atoms are there in 

 one molecule of the gas ? 



7. a) Mention three methods of increasing the speed of a reaction and give a 



practical illustration of the application of each method. 

 h) If sodium is exposed to air, what product is finally obtained ? How is 

 sodium usually preserved in the laboratory or stockroom ? 



8. What experiment would demonstrate that (a) silver nitrate contains a metal ? 



{b) sodium carbonate is a salt? (c) bromine is more active chemically 

 than iodine but less so than chlorine? {d) iron is a reducing agent? 

 (f) chlorine bleaches only indirectly ? 



9. a) In what two ways can ammonium chloride, without reacting chemically 



with any other substance, be split up into two parts ? Specify in each 

 case the conditions under which complete recombination will take place. 

 h) Why is hydrogen more rapidly evolved by zinc reacting with hydrochloric 

 acid than with acetic acid of the same concentration ? 



10. a) A certain weight of potassium carbonate, heated with 10 grams of sand, 



gives 25.6 grams of potassium silicate according to the equation 

 KoC03+SiOo = KoSi03+C02. Calculate the weight of the potassium 

 carbonate. (K 39, Si 28, O IG, C 12.) 

 b) What is the percentage of sulphur trioxide in white vitriol (ZnS04 • 7H2O) ? 

 (Zn 65, S 32, O 16, H 1.) 



11. a) Assume X to be a gaseous element having a valence of three and containing 



two atoms per molecule. To make two volumes of its gaseous compound 

 with hydrogen, how many volumes of each constituent are required ? 

 State the law upon which }-our conclusion is based. 

 b) From the standpoint of the electrolytic dissociation theory, what takes 

 place when dilute solutions of an acid and a base are mixed ? 



12. Which is the more specific term in each of the following pairs: (a) dissociation 



or ionization, {b) carbohydrates or sugars, (c) fermentation or decomposi- 

 tion, {d) halogen acids or binary acids ? Considering each of the foregoing 

 pairs separately, cite a particular case illustrating the more general term 

 which is not included by the more specific. 



13. a) Give two diflferent general methods for the formation of an acid. Illus- 



trate each by an example giving equations for the reactions involved. 

 Are there analogous methods for the formation of bases? Illustrate 

 by equations. 

 b) Sodium sulphate and copper sulphate are dissolved in separate portions 

 of pure water. Do the two solutions aflfect litmus alike ? Explain. 



(THIS EXAMINATION IS CONTINUED ON PAGE 3) ^^ 



