Question

Indicates the number of degrees of freedom of a system formed by:

a) components of the ammonia formation reaction (N2, H2, NH3) in the presence of catalyst.

b) a metallic gold surface in a nitrogen gas atmosphere and in the presence of a catalyst at a temperature of 77K.

c) a supersaturated solution of CuSO4 in water, in equilibrium with solid and vapor.

Answer 1

a) components (C): Number of independent constituents of the phases of the system in equilibrium

phase (P):Homogeneous and physically separate parts of a system

degrees of freedom (F) : Number of independent variables which represents the conditions of a system

Using phase rule: F=C-P+2 [+2 for temperature and pressure factors]

a) N2(g) +H2(g) <----> 2NH3(g) [catalyst (solid)]

P=2 (solid and gaseous)

C=4

F=4-2+2=4

b) a metallic gold surface in a nitrogen gas atmosphere and in the presence of a catalyst at a temperature of 77K

C=3 (gold ,,N2, catalyst)

P=solid and gaseous=2

F=3-2+2=3

c) a supersaturated solution of CuSO4 in water, in equilibrium with solid and vapor.

C=2 [CuSO4 , water]

P=3 [liquid,gas,solid]

F=3-2+2=3