Question

Given the values of ΔH⁰rxn, ΔS⁰rxn, and T below, determine ΔSuniv.

ΔH⁰rxn= −115 kJ , ΔS⁰rxn= 249 J/K , T= 299 K

Express your answer using two significant figures.

ΔSuniv =

Answer 1

To determine ΔSuniv, you need to calculate the entropy change of the system (ΔSsys) and the entropy change of the surroundings (ΔSsurr). Substituting the given values into the equations, ΔSsys = 249 J/K and ΔSsurr = 385.6 J/K. Therefore, ΔSuniv = 634.6 J/K.

Step-by-step explanation:

The value of ΔSuniv can be determined using the equation ΔSuniv = ΔSsys + ΔSsurr, where ΔSsys is the entropy change of the system and ΔSsurr is the entropy change of the surroundings.

In this case, ΔSsys can be calculated using the equation ΔSsys = ΔS⁰rxn - Rln(Q), where ΔS⁰rxn is the standard entropy change of the reaction and Q is the reaction quotient.

Then, ΔSsurr can be calculated using the equation ΔSsurr = -ΔH⁰rxn / T, where ΔH⁰rxn is the standard enthalpy change of the reaction and T is the temperature in Kelvin.

Substituting the given values into the equations, we have ΔSsys = 249 J/K - (8.314 J/K/mol)ln(1) = 249 J/K and ΔSsurr = -(-115 kJ) / 299 K = 385.6 J/K. Therefore, ΔSuniv = 249 J/K + 385.6 J/K = 634.6 J/K.