﻿60 
  

  

  Mixter 
  — 
  Heat 
  of 
  Formation 
  of 
  tht 
  

  

  Magnetite, 
  Fe 
  3 
  £ 
  

  

  Magnetic 
  Oxide, 
  

   Fe 
  3 
  4 
  .o5 
  

  

  Substance... 
  5*161 
  

  

  " 
  left 
  0-285 
  

  

  " 
  combined 
  (a). 
  4-876 
  

  

  Sulphur 
  1-500 
  

  

  Sodium 
  peroxide 
  20' 
  

  

  Heat 
  effect 
  10104 
  

  

  ofS 
  -7860 
  

  

  " 
  Fe._ 
  — 
  45 
  

  

  " 
  2 
  set 
  free 
  + 
  32 
  

   " 
  a 
  (b) 
  2231 
  

  

  457 
  

  

  1 
  grm. 
  

  

  6-056 
  

   0*457 
  

   5-599 
  

   1-500 
  

   20- 
  

  

  10473 
  

  

  — 
  7860 
  

  

  — 
  45 
  

   + 
  51 
  

  

  2619 
  

  

  468 
  

  

  5-615 
  

   0-520 
  

   5-095 
  

   1-500 
  

   20- 
  

  

  10087 
  

  

  - 
  7860 
  

  

  — 
  45 
  

   -h 
  V7 
  

  

  2259 
  

  

  443 
  

  

  5-910 
  grs. 
  

   0620 
  

   5-290 
  

   1-500 
  

   20- 
  

  

  10174° 
  

   —7860 
  

   — 
  45* 
  

   + 
  106 
  

  

  2375 
  

  

  449 
  

  

  a 
  

  

  The 
  mean 
  for 
  the 
  magnetite 
  is 
  462° 
  and 
  for 
  the 
  magnetic 
  

   oxide 
  446°. 
  

  

  For 
  the 
  oxidation 
  of 
  the 
  magnetite 
  we 
  have 
  2Fe 
  3 
  3 
  . 
  94 
  + 
  

   1*12 
  O 
  = 
  3Fe 
  2 
  3 
  . 
  The 
  mass 
  of 
  2Fe 
  3 
  394 
  is, 
  in 
  terms 
  of 
  atomic 
  

   weights, 
  461-12. 
  The 
  heat 
  effect 
  of 
  Ka 
  2 
  G 
  2 
  - 
  O 
  is 
  -19,400° 
  and 
  

   of 
  1-12 
  -21,700°, 
  hence 
  

  

  2Fe 
  3 
  3 
  . 
  94 
  + 
  xN%fi 
  t 
  = 
  -462° 
  X 
  461-12 
  = 
  .._ 
  213,300° 
  

  

  1-12 
  Na 
  3 
  + 
  1-120 
  = 
  _ 
  _ 
  _ 
  21,700 
  

  

  2Fe 
  3 
  394 
  + 
  1-120 
  + 
  £cNa 
  2 
  = 
  235,000 
  

  

  3Fe 
  2 
  3 
  + 
  xN&ft 
  = 
  174,000 
  

  

  2Fe 
  3 
  3 
  . 
  94 
  + 
  1-120 
  = 
  _ 
  _.. 
  61,000 
  

  

  2Fe 
  3 
  4 
  + 
  O 
  = 
  61000 
  ~ 
  1*12 
  = 
  54,500 
  

  

  For 
  the 
  heat 
  of 
  union 
  of 
  ferrous 
  with 
  ferric 
  oxide 
  we 
  have 
  

   (2FeO 
  + 
  O) 
  - 
  (2Fe 
  3 
  4 
  + 
  O) 
  = 
  9,200° 
  

   and 
  for 
  the 
  heat 
  of 
  formation 
  of 
  magnetite 
  

  

  (2Fe 
  + 
  30) 
  + 
  (Fe 
  + 
  O) 
  + 
  (FeO 
  + 
  Fe 
  2 
  3 
  ) 
  = 
  265,700° 
  

   From 
  the 
  heat 
  of 
  the 
  reaction 
  of 
  fused 
  magnetic 
  oxide 
  with 
  

   sodium 
  peroxide 
  is 
  derived 
  3Fe 
  + 
  40 
  = 
  264,600°, 
  which 
  accords 
  

   well 
  with 
  265,200°, 
  found 
  by 
  burning 
  iron 
  in 
  oxygen. 
  

  

  The 
  results 
  of 
  Berthelot* 
  and 
  LeChatelierf 
  are 
  included 
  in 
  

   the 
  following 
  summary 
  : 
  

  

  B. 
  LeC. 
  

  

  64,600°* 
  

   198,400 
  \ 
  

  

  (900') 
  

   (faint 
  red) 
  

   (magnetite) 
  

   (fused) 
  

  

  Fe 
  4- 
  O 
  = 
  FeO 
  

  

  2Fe 
  + 
  30 
  = 
  Fe 
  2 
  3 
  

  

  3Fe 
  + 
  40 
  = 
  Fe 
  3 
  4 
  

  

  3Fe 
  + 
  40 
  = 
  Fe 
  3 
  4 
  

  

  2FeO 
  + 
  O 
  = 
  Fe 
  2 
  3 
  

  

  2Fe 
  3 
  4 
  + 
  O 
  = 
  3Fe,0, 
  

  

  FeO 
  + 
  Fe 
  2 
  3 
  = 
  Fe 
  3 
  4 
  (magnetite) 
  

  

  Fe 
  2 
  3 
  + 
  ccNa 
  2 
  = 
  aNa,O.Fe 
  3 
  3 
  

  

  *Ann. 
  Chim. 
  Phys. 
  (5), 
  xxiii, 
  118. 
  

   X 
  Experimental 
  result. 
  

  

  + 
  

   + 
  

   + 
  

   + 
  

   + 
  

   + 
  

   4- 
  

  

  tc. 
  

  

  64,300°§. 
  

  

  192,200 
  §.. 
  

  

  265,700 
  §.. 
  

  

  265,200 
  J. 
  

  

  63,700 
  §.. 
  

  

  54,500 
  §. 
  

  

  9,200 
  §. 
  

  

  58,000 
  J.. 
  

  

  R., 
  cxx, 
  623. 
  

  

  268,800§ 
  

  

  65,200 
  § 
  

  

  Derived 
  result. 
  

  

  