QUESTIONS AND PROBLEMS 123 



*8o. Determine the water of crystallisation in the sodium sulphate, and 

 ascribe a formula to the crystallised salt. 



Common Salt : Hydrochloric Acid. 



81. What is the characteristic crystalline form of common salt ? Is the 



pure substance deliquescent, or to what impurity is the deliquei;- 

 cence due ? 



82. Hydrochloric acid and common salt not being compounds of oxygen, 



give a definition of acids and salts which will include these two 

 compounds as well as oxygenated compounds. 

 2)^. Hydrochloric acid being volatile, use may be made of the same 

 method for its preparation that was found to serve for the prepara- 

 tion of sulphurous acid gas from its compounds. Fully describe 

 such a method of preparation, and give a drawing of the apparatus 

 employed. 



84. What are the properties of hydrochloric acid gas in respect to density, 



combustibility, colour, taste and smell, and solubility in water? 

 Why is it to be expected that the gas would not support com- 

 bustion ? 



85. By what physical method may the strength of a solution of hydro- 



chloric acid be determined ? 



86. How would you prove that caustic soda and hydrochloric acid react 



in accordance with the equation — 



HCH- NaOH = NaCl + H2O ? 



?>'J. In what proportion does chloride of sodium exist in sea water ? To 



what are the deliquescent properties of sea salt due ? From what 



elements are the bromides and iodides derived, which also exist in 



sea water in very minute quantities ? 

 ^^. Why was chloride of potassium first called "muriate of potash"? 



How may it be prepared from " carnal! ite," the double chloride of 



potassium and magnesium? What is "kainite," and for what 



purpose is it employed ? 

 89. How may chlorides be distinguished from the salts of other common 



acids ? 

 *90. Prepare a bottle full of hydrochloric acid gas. 

 *9i. Volumetrically determine the strength of the hydrochloric acid 



solution. Confirm by its relative density. 

 *92. Identify the three acids. (Sulphurous, sulphuric, and hydrochloric 



acids. ) 

 *93. Examine the tap water and the drainage water for chlorides and 



sulphates. 



