COLLATERAL READING 21 



for certain ions these values are open to question as the results of different 

 investigations do not agree. It seems certain, however, that both anions and 

 cations are hydrated, and that for some kinds of ions, at least, as many as a 

 hundred or more molecules of water of hydration may be associated with a 

 single ion. 



Discussion Questions 



1. Describe the appearance of a solution of sucrose in water assuming you 



were small enough to stand between the water molecules. Do the same 

 for a solution of sodium chloride. What changes would be observed upon 

 a rise in temperature? 



2. How would you prepare a volume molar solution of glucose (C6H12O6), 



NaCl, CaCl2-4H20, MgSOi-yH^O? Weight molar solutions of the 

 same compounds? 



3. Given a volume molar solution, how would you prepare 125 cc. of a 0.75 



volume molar solution? Given a 0.5 volume molar solution, how would 

 you prepare 50 cc. of a 0.225 volume molar solution? 



4. What is the weight molar concentration of a 20 per cent sucrose solution? 



5. When a weight molar solution of sucrose is prepared by adding 342.2 g. of 



sucrose to i liter of water the volume of the resulting solution is 1207 cc. 

 at 0° C. What is its volume molar concentration? 



6. How much water must be added to the 1207 cc. of weight molar solution 



(question 5) in order to convert it into a 0.5 weight molar solution? 



7. How much 0.2 N NaOH would be required to neutralize 100 cc. 1 N HCl? 



8. If 15 cc. of KOH solution requires 17.5 cc. of i N HCl solution to neutralize 



it, what is the normality of the KOH solution? 



9. If an electrolyte which produces two ions is 50 per cent dissociated what 



will be the per cent of dissolved particles (ions plus molecules) in the 

 solution in terms of the number of particles which would be present if no 

 dissociation occurred? If the electrolyte were 75 per cent dissociated? 

 Answer the same questions for an electrolyte which produces three ions. 



10. If the pH of a molar solution of hydrochloric acid is o.i, and the pH of 



a molar solution of acetic acid 2.37, what would the total acidity of each 

 of these two solutions be? 



11. How much greater is the concentration of hydrogen ions in a solution of 



pH 4 than one of pH 7? One of pH 3 than of pH 9? 



12. How much greater is the concentration of hydroxyl ions in a solution of 



pH 13 than one of pH 10? One of pH 8 than one of pH 5? 



13. Why will an increase in the CO2 content of water result in an increase in 



its H-ion concentration? 



14. Why will the addition of a base to water decrease the concentration of 



hydrogen ions present? 



15. In two determinations of the pH of a solution an investigator obtained 



values of 6.0 and 6.4. He concluded that an average value for the pH of 

 the solution was 6.2. Evaluate. 



Suggested for Collateral Reading 



Bayliss, W. ]\I. Principles of general physiology. 4th Ed. Longmans, 

 Green and Co. London. 1924. 



