Question

Consider the reaction between nitrogen and oxygen gas to form dinitrogen monoxide:

2N2(g)+O2(g)?2N2O(g),?Hrxn=+163.2kJ Calculate the entropy change in the surroundings associated with this reaction occurring at 25?C.
Determine the sign of the entropy change for the system and the universe.

Answer 1

The entropy change in the surroundings can be calculated using the equation ΔSsurr = -ΔH/T, where ΔSsurr is the entropy change in the surroundings, ΔH is the enthalpy change, and T is the temperature in Kelvin. The entropy change in the surroundings for this reaction is -0.547 kJ/K. The entropy change for the system and the universe is positive due to the endothermic nature of the reaction.

Step-by-step explanation:

The entropy change in the surroundings can be calculated using the equation:

ΔSsurr = -ΔH/T

Where ΔSsurr is the entropy change in the surroundings, ΔH is the enthalpy change, and T is the temperature in Kelvin.

Using the value for ΔH of +163.2 kJ and the temperature of 25°C, which is 298 K, the entropy change in the surroundings can be calculated as:

ΔSsurr = -(+163.2 kJ) / 298 K

ΔSsurr = -0.547 kJ/K

The sign of the entropy change for the system and the universe can be determined by considering the fact that the reaction is endothermic. Since endothermic reactions absorb heat from the surroundings, the entropy change for the system is positive and the entropy change for the universe is also positive.