In each he fills a reaction vessel with some mixture of the reactants and produc

Question

In each he fills a reaction vessel with some mixture of the reactants and products at a constant temperature of 120.0 degree C and constant total pressure. Then, he measures the reaction enthalpy delta H and reaction entropy delta S of the first reaction, and the reaction enthalpy delta H and reaction free energy delta G of the second reaction. The results of his measurements are shown in the table. Complete the table. That is, calculate delta G for the first reaction and delta S for the second. (Make sure any you enter have the correct number of significant digits.) Then, decide whether, under the conditions the engineer has set up, the reaction is spontaneous, the reverse reaction is spontaneous, or neither forward nor reverse reaction is spontaneous because the system is at equilibrium.

Explanation / Answer

1)

H = 803.0 KJ

S = 2042J/K = 2.042 KJ/K

T = 120.0 oC =(120.0+ 273) K = 393.0 K

use:

G = H - T*S

G = 803.0 - 393.0 * 2.042

G = 0.494 KJ/mol

Since G    is positive, the reaction is spontaneous in reverse direction

2)

G = -28.0 KJ

H = -70.0 KJ

T = 120.0 oC =(120.0+ 273) K = 393.0 K

use:

G = H - T*S

-28.0 = -70.0 - 393.0 * S

S = -0.11 KJ/K

S = -107 J/K

Since G    is negative, the reaction is spontaneous

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