316 SMITH'S INTERMEDIATE CHEMISTRY 



To balance the second equation, hydrogen atoms must be supplied 

 in pairs, so the HOC1 must be multiplied by two: 



Balanced: 2HOC1 -> H 2 O + C1 2 O. 



With nitric acid the operation is similar: 



Skeleton: HN0 3 ^H 2 + ? 



Balanced: 2HNO 3 -> H 2 O + N 2 5 . 



This operation should be practiced : 



Skeleton: HC1O 4 - H 2 + ? H 3 P0 4 - H 2 O + ? 



Balanced: 2HC10 4 -> H 2 O + ? 2H 3 P0 4 -> 3H 2 + ? 



The valence of the characteristic non-metal is ascertained by this 

 process. What is the valence of Cl in HOC1? The anhydride is 

 C1 2 O. The valence is Cl 1 . What is the valence of S in H 2 S0 4 ? 

 The anhydride is SO 3 . The valence is S VI . What is the valence 

 of N in HN0 3 ? The anhydride N 2 05 shows the valence to be N v . 

 What are the valences of Cl in HC10 4 and of P in H 3 P0 4 and in 

 HP0 3 ? 



When we get SO 2 from sulphuric acid, by a chemical action, how 

 do we know that the acid has been reduced (and something else 

 oxidized)? Because in sulphuric acid we have S VI 3 n , and in the 

 product S IV 2 n . The valence of S has been lowered from VI to 

 IV. When from nitric acid we get N 2 Os, has there been reduction? 

 No, because N 2 5 + H 2 = 2HN0 3 (nitric acid). If we get 

 NO 2 or NO, has there been reduction of the acid? Yes, because 

 the valence has been reduced: N IV 2 , N n O. We then proceed 

 to pick out the other substance that has been oxidized. 



Analyzing the formula of the acid, to get that of the anhydride, 

 also aids us to balance equations. 



Balancing Equations. When dilute nitric acid acts upon 

 copper, the following skeleton equation represents the products 

 of the reaction. 

 Skeleton: Cu + HNO 3 - Cu(NO 3 ) 2 + NO + H 2 0. 



