GROUP IV 171
- THE REACTIONS WITH ALKALIS
Carbon
Carbon does not react, even with molten alkali.
Silicon and germanium
Silicon and germanium readily react with even very dilute solutions
of caustic alkali. Silicon is so sensitive to attack that it will dissolve
when boiled with water which has been in contact with glass*:
Si + 2OH" + H 2 O -> SiO|" 4- 2H 2 |
Ge + 2OH- + H 2 O -> GeO§- + 2H 2 t
Tin
Tin dissolves slowly in hot concentrated alkali forming a hexa-
hydroxostannate(IV):
Sn + 4H 2 O + 2OH~ -> [Sn(OH) 6 ]^2 " -f 2H 2 |
Lead
Lead dissolves only very slowly in hot concentrated sodium
hydroxide and forms hexahydroxoplumbate(II):
Pb + 4OH~ + 2H 2 O -> [Pb(OH) 6 ]^4 ~ + H 2 |
Notice, again, that the lower oxidation state of lead is formed.
- THE REACTIONS WITH OXYGEN
Carbon
All forms of carbon, if heated to a sufficiently high temperature, give
carbon dioxide in a plentiful supply of air, and carbon monoxide if
the supply is limited (p. 178):
C + O 2 -> CO 2 :AH=- 394 kJ mol"^1
C + iO^CO: AH = - lllkJmor^1
- The equations are simplified: the oxosilicates and germanates actually formed
are complex.
