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Unformatted text preview: in more than one phase Example: 3 Fe (s) + K c = ¾¾
4 H2O (g) ¬¾ ¾ [H 2 ]4 [H 2 O]4 Fe3O4 (s) + 4 H2 (g) NOTE: The concentrations of so lids are omitted. Reason: The concentration of a pure solid or pure liquid is a constant at a given temperature. · Equilibrium Constant expressio n can be written with pure solids included: [Fe 3 O 4 ] [H 2 ]4 K c = 3 4 [Fe] [H 2 O] 3 [Fe] [H 2 ]4 By rearrangement: K c = [Fe O ] [H 2 O]4 3 4 constant factors variable factors 3 [Fe] [H 2 ]4 K ' = K c = c
[Fe 3O 4 ] [H 2 O]4 · The concentrations of pure solids and liquids are incorporated in the value o f Kc’ . · The concentration of so lvent is also omitted from the expression o f Kc for a ho mogeneous reaction (if constant).
· The equilibrium is not affected by pure solids, pure liquids, or solvents. 11 Chemistry 102 Chapter 14 Examples: Ident ify each of the fo llowing equilibriums as ho mogeneous or heterogeneous and write Kc expressio ns for each: 1. ¾¾
FeO (s) + H2 (g) ¬¾ Fe (s)...
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