2. Using the principals of thermodynamics and molecular kinetic collision theory

Question

2. Using the principals of thermodynamics and molecular kinetic collision theory, answer the questions regarding the spontaneous system shown below at 298 K CO2 (g) + 2 NH3 (g)-> CO(NH2)2 (s) + H20 (1) AHr 134 kJ Is the entropy change f the phases of each molecule AND the number of moles in your answer). (3 points) a. or the reaction positive or negative? Justify your response (Hint: consider Which factor is responsible for the reaction being spontaneous, the enthalpy of reaction or entropy of reaction? Justify your answer using the governing equation between free energy enthalpy, entropy and temperature. (3 points) b. Will there be a temperature at which reaction become non-spontaneous? Justify using the governing equation between free energy, enthalpy, entropy and tem your answer perature. (3 points) c.

Explanation / Answer

Part a

Entropy increases when number of moles in the system increases and vice versa.

Entropy increases when phase changes from from solid to liquid and liquid to gas phase and vice versa.

From the given reaction

Phase change occurs from gas to solid and gas to liquid phase and Moles of system decreases from 3 to 2 as the reaction proceeds.

Therefore the entropy decreases or the entropy change will be negative.

Part b

The reaction becomes spontaneous when standard free energy

G < 0

For the given reaction H < 0

For the given reaction S < 0

The equation

G = H - TS

G < 0

The reaction is spontaneous

Part C

When G > 0, the reaction become non spontaneous

G = H - TS

When the temperature is very high, G > 0

At high temperatures, the reaction becomes non spontaneous.

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