QUESTIONS AND ANSWERS 9 



Distinguish between a mixture and a compound. 



A mixture consists of a combination of two or more substances 

 each of which retains its individual characteristics and may be 

 separated from each other by mechanical means, no matter how 

 thoroughly mixed and finely commingled. Example: Iron filings 

 and sulphur may be mixed and if no heat is added, the iron can be 

 removed from the mixture with an electromagnet ; if heat had been 

 added to the mixture, a compound, ferrous sulphide (PeS) would 

 have been formed, which would require chemical means to separate. 



Distinguish betvreen a metal and a non-metal. 



See "metals," p. 5. Non-metals do not possess a metallic 

 appearance and are known as metalloids. To these belong sulphur, 

 carbon, phosphorus, oxygen, etc. The line between metals and non- 

 metals^is not very marked. Thus, mercury, despite the fact that 

 it iJM^^at ordinary temperature, must be included among the 

 metafl^^Kse of its chemical properties. 

 Mention (a) three light metals and (b) three heavy metals. Give the 

 ^^bol and atomic v^eight of each. 



(^^Lluminum, Al, 26.9 ; sodium, Na, 23 ; potassium, K, 39. 



(b) Gold, Au, 195.7 ; lead, Pb, 205 ; iron, Fe, 56. 



Name ten non-metallic elements and write the symbol of each. 



Hydrogen, H; oxygen, 0; nitrogen, N; sulphur, S; carbon, G; 

 phosphorus, P ; chlorine, CI ; bromine, Br ; iodine, I ; fluorine, F. 



Complete the following equations : ^ 



1. HCl + AgN03= ^^£X ^ <IK*^*> 



2. 2NH^0H + H^SO^ = ^ '-vt ui^^^Y ^iHm « 



3. Hjd-fNa= )«^ -'H 



1.' HCl + AgNOs = AgCl + HNO3. 



2. 2NH,0H + H,SO, = (NHJ.SO, + 2H,0. 



3. H^O + Na = NaOH + H. 

 Complete the following equations : 



1. AgN03 + KCl= IV> 



2. ZnCl, + 2K0H = ^m ^''£^ 



4. 3HC1 + HN03= ^ A 



5. Ca(0H), + 2NH,Cl=fe<^^^ v^V'* 



1. AgNOa + KCl = AgCl + KNO3. 



2. ZnCl^ + 2K0H = 2KC1 + Zn(OH),. 



3. CaF^ + H2SO, = 2HF + CaSO,. 



4. 3HC1 + HNQ3 = 2H,0 + NO -f 3C1. 



5. Ca(6H), + 2NH,C1 - CaCl, + 2(NH,0H). 



