APPLICATION OF THE MOLECULAR HYPOTHESIS 97 



arranging themselves in a continuation of the crystal pattern. 

 Equilibrium relations between crystals and vapor resemble closely, 

 therefore, those between liquid and vapor discussed in an earlier 

 chapter (p. 62-4), to which reference should here be made. 



Exercises. 1. State the change which takes place in the total 

 volume of the gases or vapors in each of the six actions mentioned, 

 p. 72. 



2. If 1 liter of oxygen at and 760 mm. weighs 1.429 g., what 

 is the molecular weight (pp. 74, 84)? 



3. Calculate the molecular weight of a gas, 200 c.c. of which at 

 and 760 mm. weigh 2.1 g. (p. 85). 



4. Find the molecular weight of a gas, of which 250 c.c. at 18 

 and 752 mm. weigh 2.5 g. (p. 85). 



5. The following are the weights of sulphur contained in the 

 molecular weights of several of its compounds: 32.06, 64.12, 

 96.18. What is the atomic weight of sulphur (pp. 74, 76)? 



6. What information is contained in each of the formulae: 82, 

 PC1 3 , A1 2 3 (p. 79)? 



7. If two gases combine in the ratio 5 : 2 by volume, in what 

 relative numbers do their molecules interact (p. 82)? 



8. The density of sulphur dioxide is 0.00286. What is its 

 molecular weight (p. 85)? 



9. The density of a gas, air = 1, is 2.3. What is its molecular 

 weight (p. 85)? 



10. An element combines with hydrogen in the proportion 

 10.03 : 1, and its specific heat is 0.2. What is its atomic weight 

 (p. 87)? 



11. The molecular formula of a gas is CH 4 . What is the gram- 

 molecular weight? What volume does this weight occupy? 

 What is the weight of 1 liter of the gas? 



