MAKING OF FORMULA AND EQUATIONS 107 



given in the table on the rear cover, must be made into molecular 

 formulae before use in equations. 



Exercises. 1. Using the data given on p. 35, calculate the 

 formulae of sulphur dioxide, phosphorus pentoxide, and carbon 

 dioxide. 



2. Using the 'results of 1, make and balance the equations for 

 the union of each of the three elements, sulphur, phosphorus, and 

 carbon, with oxygen. 



3. Using the information on p. 36, make and balance the 

 equations for the interaction with oxygen of: (a) carbon disul- 

 phide (082); (b) zinc sulphide (zinc oxide is ZnO), and (c) wood 

 (assuming the formula of the latter to be that of cellulose, C 6 Hi 5 ). 



4. Make and balance the equations for the actions on water 

 of: (a) potassium (giving KOH), and (6) calcium (giving Ca0 2 H 2 , 

 usually written Ca(OH) 2 ). 



5. Using the data in regard to the action of zinc on hydro- 

 chloric acid, given on p. 53, calculate the formula of zinc chloride 

 and make the equation. 



6. Make equations for the action of magnesium and aluminium 

 upon hydrochloric acid (giving MgCl 2 and Aids) and upon sul- 

 phuric acid (giving MgS0 4 and A1 2 (S0 4 )3). 



7. Make a molecular equation for the decomposition of hydro- 

 chloric acid by electrolysis (p. 55). 



8. Make equations for the formation of the hydrates of sodium 

 carbonate (NaaCOg, 10H 2 O) and of cupric sulphate (CuSO 4 ,5H 2 O), 

 by union of the anhydrous substances with water. 



